{"id":14874,"date":"2025-06-10T15:51:02","date_gmt":"2025-06-10T08:51:02","guid":{"rendered":"https:\/\/www.ckconitsha.com\/vn\/?p=14874"},"modified":"2025-07-05T15:50:04","modified_gmt":"2025-07-05T08:50:04","slug":"danh-sach-cac-quy-tac-toan-hoc-lop-4-day-du-chi-tiet-nhat","status":"publish","type":"post","link":"https:\/\/www.ckconitsha.com\/vn\/danh-sach-cac-quy-tac-toan-hoc-lop-4-day-du-chi-tiet-nhat\/","title":{"rendered":"Danh s\u00e1ch c\u00e1c quy t\u1eafc to\u00e1n h\u1ecdc l\u1edbp 4 \u0111\u1ea7y \u0111\u1ee7 chi ti\u1ebft nh\u1ea5t"},"content":{"rendered":"<div id=\"ez-toc-container\" class=\"ez-toc-v2_0_79_2 counter-hierarchy ez-toc-counter ez-toc-grey ez-toc-container-direction\">\n<div class=\"ez-toc-title-container\">\n<p class=\"ez-toc-title\" style=\"cursor:inherit\">Table of Contents<\/p>\n<span class=\"ez-toc-title-toggle\"><\/span><\/div>\n<nav><ul class='ez-toc-list ez-toc-list-level-1 ' ><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-1\" href=\"https:\/\/www.ckconitsha.com\/vn\/danh-sach-cac-quy-tac-toan-hoc-lop-4-day-du-chi-tiet-nhat\/#Tong_hop_cac_quy_tac_toan_hoc_lop_4_day_du_nhat\" >T\u1ed5ng h\u1ee3p c\u00e1c quy t\u1eafc to\u00e1n h\u1ecdc l\u1edbp 4 \u0111\u1ea7y \u0111\u1ee7 nh\u1ea5t<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-2\" href=\"https:\/\/www.ckconitsha.com\/vn\/danh-sach-cac-quy-tac-toan-hoc-lop-4-day-du-chi-tiet-nhat\/#On_tap_ve_so_tu_nhien\" >\u00d4n t\u1eadp v\u1ec1 s\u1ed1 t\u1ef1 nhi\u00ean<\/a><ul class='ez-toc-list-level-4' ><li class='ez-toc-heading-level-4'><a class=\"ez-toc-link ez-toc-heading-3\" href=\"https:\/\/www.ckconitsha.com\/vn\/danh-sach-cac-quy-tac-toan-hoc-lop-4-day-du-chi-tiet-nhat\/#_So_va_chu_so\" >* S\u1ed1 v\u00e0 ch\u1eef s\u1ed1<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-4'><a class=\"ez-toc-link ez-toc-heading-4\" href=\"https:\/\/www.ckconitsha.com\/vn\/danh-sach-cac-quy-tac-toan-hoc-lop-4-day-du-chi-tiet-nhat\/#_Hang_va_lop\" >* H\u00e0ng v\u00e0 l\u1edbp<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-5\" href=\"https:\/\/www.ckconitsha.com\/vn\/danh-sach-cac-quy-tac-toan-hoc-lop-4-day-du-chi-tiet-nhat\/#Day_so\" >D\u00e3y s\u1ed1<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-6\" href=\"https:\/\/www.ckconitsha.com\/vn\/danh-sach-cac-quy-tac-toan-hoc-lop-4-day-du-chi-tiet-nhat\/#Phep_cong\" >Ph\u00e9p c\u1ed9ng<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-7\" href=\"https:\/\/www.ckconitsha.com\/vn\/danh-sach-cac-quy-tac-toan-hoc-lop-4-day-du-chi-tiet-nhat\/#Phep_tru\" >Ph\u00e9p tr\u1eeb<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-8\" href=\"https:\/\/www.ckconitsha.com\/vn\/danh-sach-cac-quy-tac-toan-hoc-lop-4-day-du-chi-tiet-nhat\/#Cac_quy_tac_toan_hoc_lop_4_ve_phep_nhan\" >C\u00e1c quy t\u1eafc to\u00e1n h\u1ecdc l\u1edbp 4 v\u1ec1 ph\u00e9p nh\u00e2n<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-9\" href=\"https:\/\/www.ckconitsha.com\/vn\/danh-sach-cac-quy-tac-toan-hoc-lop-4-day-du-chi-tiet-nhat\/#Phep_chia\" >Ph\u00e9p chia<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-10\" href=\"https:\/\/www.ckconitsha.com\/vn\/danh-sach-cac-quy-tac-toan-hoc-lop-4-day-du-chi-tiet-nhat\/#Tinh_chat_chia_het_cua_day_so_tu_nhien\" >T\u00ednh ch\u1ea5t chia h\u1ebft c\u1ee7a d\u00e3y s\u1ed1 t\u1ef1 nhi\u00ean<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-11\" href=\"https:\/\/www.ckconitsha.com\/vn\/danh-sach-cac-quy-tac-toan-hoc-lop-4-day-du-chi-tiet-nhat\/#Toan_Trung_binh_cong\" >To\u00e1n Trung b\u00ecnh c\u1ed9ng<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-12\" href=\"https:\/\/www.ckconitsha.com\/vn\/danh-sach-cac-quy-tac-toan-hoc-lop-4-day-du-chi-tiet-nhat\/#Cac_quy_tac_toan_hoc_lop_4_ve_toan_ti_le_thuan\" >C\u00e1c quy t\u1eafc to\u00e1n h\u1ecdc l\u1edbp 4 v\u1ec1 to\u00e1n t\u1ec9 l\u1ec7 thu\u1eadn<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-13\" href=\"https:\/\/www.ckconitsha.com\/vn\/danh-sach-cac-quy-tac-toan-hoc-lop-4-day-du-chi-tiet-nhat\/#Toan_ti_le_nghich\" >To\u00e1n t\u1ec9 l\u1ec7 ngh\u1ecbch<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-14\" href=\"https:\/\/www.ckconitsha.com\/vn\/danh-sach-cac-quy-tac-toan-hoc-lop-4-day-du-chi-tiet-nhat\/#Ti_so_phan_tram\" >T\u1ec9 s\u1ed1 ph\u1ea7n tr\u0103m<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-15\" href=\"https:\/\/www.ckconitsha.com\/vn\/danh-sach-cac-quy-tac-toan-hoc-lop-4-day-du-chi-tiet-nhat\/#Cac_quy_tac_toan_hoc_lop_4_ve_dai_luong\" >C\u00e1c quy t\u1eafc to\u00e1n h\u1ecdc l\u1edbp 4 v\u1ec1 \u0111\u1ea1i l\u01b0\u1ee3ng<\/a><ul class='ez-toc-list-level-4' ><li class='ez-toc-heading-level-4'><a class=\"ez-toc-link ez-toc-heading-16\" href=\"https:\/\/www.ckconitsha.com\/vn\/danh-sach-cac-quy-tac-toan-hoc-lop-4-day-du-chi-tiet-nhat\/#_Bang_don_vi_do_do_dai\" >* B\u1ea3ng \u0111\u01a1n v\u1ecb \u0111o \u0111\u1ed9 d\u00e0i<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-4'><a class=\"ez-toc-link ez-toc-heading-17\" href=\"https:\/\/www.ckconitsha.com\/vn\/danh-sach-cac-quy-tac-toan-hoc-lop-4-day-du-chi-tiet-nhat\/#_Bang_don_vi_do_khoi_luong\" >* B\u1ea3ng \u0111\u01a1n v\u1ecb \u0111o kh\u1ed1i l\u01b0\u1ee3ng<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-4'><a class=\"ez-toc-link ez-toc-heading-18\" href=\"https:\/\/www.ckconitsha.com\/vn\/danh-sach-cac-quy-tac-toan-hoc-lop-4-day-du-chi-tiet-nhat\/#_Bang_don_vi_do_dien_tich\" >* B\u1ea3ng \u0111\u01a1n v\u1ecb \u0111o di\u1ec7n t\u00edch<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-4'><a class=\"ez-toc-link ez-toc-heading-19\" href=\"https:\/\/www.ckconitsha.com\/vn\/danh-sach-cac-quy-tac-toan-hoc-lop-4-day-du-chi-tiet-nhat\/#_Bang_don_vi_do_the_tich\" >* B\u1ea3ng \u0111\u01a1n v\u1ecb \u0111o th\u1ec3 t\u00edch<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-4'><a class=\"ez-toc-link ez-toc-heading-20\" href=\"https:\/\/www.ckconitsha.com\/vn\/danh-sach-cac-quy-tac-toan-hoc-lop-4-day-du-chi-tiet-nhat\/#_Cac_quy_tac_toan_hoc_lop_4_ve_Giay_%E2%80%93_the_ky\" >* C\u00e1c quy t\u1eafc to\u00e1n h\u1ecdc l\u1edbp 4 v\u1ec1 Gi\u00e2y \u2013 th\u1ebf k\u1ef7<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-21\" href=\"https:\/\/www.ckconitsha.com\/vn\/danh-sach-cac-quy-tac-toan-hoc-lop-4-day-du-chi-tiet-nhat\/#On_tap_hinh_hoc\" >\u00d4n t\u1eadp h\u00ecnh h\u1ecdc<\/a><ul class='ez-toc-list-level-4' ><li class='ez-toc-heading-level-4'><a class=\"ez-toc-link ez-toc-heading-22\" href=\"https:\/\/www.ckconitsha.com\/vn\/danh-sach-cac-quy-tac-toan-hoc-lop-4-day-du-chi-tiet-nhat\/#_Hinh_vuong\" >* H\u00ecnh vu\u00f4ng<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-4'><a class=\"ez-toc-link ez-toc-heading-23\" href=\"https:\/\/www.ckconitsha.com\/vn\/danh-sach-cac-quy-tac-toan-hoc-lop-4-day-du-chi-tiet-nhat\/#_Hinh_chu_nhat\" >* H\u00ecnh ch\u1eef nh\u1eadt<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-4'><a class=\"ez-toc-link ez-toc-heading-24\" href=\"https:\/\/www.ckconitsha.com\/vn\/danh-sach-cac-quy-tac-toan-hoc-lop-4-day-du-chi-tiet-nhat\/#_Hinh_binh_hanh\" >* H\u00ecnh b\u00ecnh h\u00e0nh<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-4'><a class=\"ez-toc-link ez-toc-heading-25\" href=\"https:\/\/www.ckconitsha.com\/vn\/danh-sach-cac-quy-tac-toan-hoc-lop-4-day-du-chi-tiet-nhat\/#_Hinh_thoi\" >* H\u00ecnh thoi<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-4'><a class=\"ez-toc-link ez-toc-heading-26\" href=\"https:\/\/www.ckconitsha.com\/vn\/danh-sach-cac-quy-tac-toan-hoc-lop-4-day-du-chi-tiet-nhat\/#_Hinh_thang\" >* H\u00ecnh thang<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-4'><a class=\"ez-toc-link ez-toc-heading-27\" href=\"https:\/\/www.ckconitsha.com\/vn\/danh-sach-cac-quy-tac-toan-hoc-lop-4-day-du-chi-tiet-nhat\/#_Hinh_tam_giac\" >* H\u00ecnh tam gi\u00e1c<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-4'><a class=\"ez-toc-link ez-toc-heading-28\" href=\"https:\/\/www.ckconitsha.com\/vn\/danh-sach-cac-quy-tac-toan-hoc-lop-4-day-du-chi-tiet-nhat\/#_Hinh_tron\" >* H\u00ecnh tr\u00f2n<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-4'><a class=\"ez-toc-link ez-toc-heading-29\" href=\"https:\/\/www.ckconitsha.com\/vn\/danh-sach-cac-quy-tac-toan-hoc-lop-4-day-du-chi-tiet-nhat\/#_Hinh_hop_chu_nhat\" >* H\u00ecnh h\u1ed9p ch\u1eef nh\u1eadt<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-4'><a class=\"ez-toc-link ez-toc-heading-30\" href=\"https:\/\/www.ckconitsha.com\/vn\/danh-sach-cac-quy-tac-toan-hoc-lop-4-day-du-chi-tiet-nhat\/#_Hinh_lap_phuong\" >* H\u00ecnh l\u1eadp ph\u01b0\u01a1ng<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-31\" href=\"https:\/\/www.ckconitsha.com\/vn\/danh-sach-cac-quy-tac-toan-hoc-lop-4-day-du-chi-tiet-nhat\/#Cac_quy_tac_toan_hoc_lop_4_ve_phan_so_va_cac_phep_tinh_phan_so\" >C\u00e1c quy t\u1eafc to\u00e1n h\u1ecdc l\u1edbp 4 v\u1ec1 ph\u00e2n s\u1ed1 v\u00e0 c\u00e1c ph\u00e9p t\u00ednh ph\u00e2n s\u1ed1<\/a><ul class='ez-toc-list-level-4' ><li class='ez-toc-heading-level-4'><a class=\"ez-toc-link ez-toc-heading-32\" href=\"https:\/\/www.ckconitsha.com\/vn\/danh-sach-cac-quy-tac-toan-hoc-lop-4-day-du-chi-tiet-nhat\/#_Khai_niem_phan_so\" >* Kh\u00e1i ni\u1ec7m ph\u00e2n s\u1ed1<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-4'><a class=\"ez-toc-link ez-toc-heading-33\" href=\"https:\/\/www.ckconitsha.com\/vn\/danh-sach-cac-quy-tac-toan-hoc-lop-4-day-du-chi-tiet-nhat\/#_So_sanh_cac_phan_so\" >* So s\u00e1nh c\u00e1c ph\u00e2n s\u1ed1<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-4'><a class=\"ez-toc-link ez-toc-heading-34\" href=\"https:\/\/www.ckconitsha.com\/vn\/danh-sach-cac-quy-tac-toan-hoc-lop-4-day-du-chi-tiet-nhat\/#_Cac_phep_tinh_phan_so\" >* C\u00e1c ph\u00e9p t\u00ednh ph\u00e2n s\u1ed1<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-4'><a class=\"ez-toc-link ez-toc-heading-35\" href=\"https:\/\/www.ckconitsha.com\/vn\/danh-sach-cac-quy-tac-toan-hoc-lop-4-day-du-chi-tiet-nhat\/#_Tim_phan_so_cua_mot_so\" >* T\u00ecm ph\u00e2n s\u1ed1 c\u1ee7a m\u1ed9t s\u1ed1<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-4'><a class=\"ez-toc-link ez-toc-heading-36\" href=\"https:\/\/www.ckconitsha.com\/vn\/danh-sach-cac-quy-tac-toan-hoc-lop-4-day-du-chi-tiet-nhat\/#_Tim_mot_so_biet_gia_tri_phan_so_cua_so_do\" >* T\u00ecm m\u1ed9t s\u1ed1 bi\u1ebft gi\u00e1 tr\u1ecb ph\u00e2n s\u1ed1 c\u1ee7a s\u1ed1 \u0111\u00f3<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-37\" href=\"https:\/\/www.ckconitsha.com\/vn\/danh-sach-cac-quy-tac-toan-hoc-lop-4-day-du-chi-tiet-nhat\/#On_tap_tim_hai_so_khi_biet_tong_hoac_hieu_va_ti_cua_hai_so_do\" >\u00d4n t\u1eadp t\u00ecm hai s\u1ed1 khi bi\u1ebft t\u1ed5ng ho\u1eb7c hi\u1ec7u v\u00e0 t\u1ec9 c\u1ee7a hai s\u1ed1 \u0111\u00f3<\/a><ul class='ez-toc-list-level-4' ><li class='ez-toc-heading-level-4'><a class=\"ez-toc-link ez-toc-heading-38\" href=\"https:\/\/www.ckconitsha.com\/vn\/danh-sach-cac-quy-tac-toan-hoc-lop-4-day-du-chi-tiet-nhat\/#_Tong_va_hieu\" >* T\u1ed5ng v\u00e0 hi\u1ec7u<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-4'><a class=\"ez-toc-link ez-toc-heading-39\" href=\"https:\/\/www.ckconitsha.com\/vn\/danh-sach-cac-quy-tac-toan-hoc-lop-4-day-du-chi-tiet-nhat\/#_Tong_va_ti\" >* T\u1ed5ng v\u00e0 t\u1ec9<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-4'><a class=\"ez-toc-link ez-toc-heading-40\" href=\"https:\/\/www.ckconitsha.com\/vn\/danh-sach-cac-quy-tac-toan-hoc-lop-4-day-du-chi-tiet-nhat\/#_Hieu_va_ti\" >* Hi\u1ec7u v\u00e0 t\u1ec9<\/a><\/li><\/ul><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-41\" href=\"https:\/\/www.ckconitsha.com\/vn\/danh-sach-cac-quy-tac-toan-hoc-lop-4-day-du-chi-tiet-nhat\/#Bi_quyet_hoc_cac_quy_tac_toan_hoc_lop_4_hieu_qua\" >B\u00ed quy\u1ebft h\u1ecdc c\u00e1c quy t\u1eafc to\u00e1n h\u1ecdc l\u1edbp 4 hi\u1ec7u qu\u1ea3<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-42\" href=\"https:\/\/www.ckconitsha.com\/vn\/danh-sach-cac-quy-tac-toan-hoc-lop-4-day-du-chi-tiet-nhat\/#Ket_luan\" >K\u1ebft lu\u1eadn<\/a><\/li><\/ul><\/nav><\/div>\n<\/p>\n<p>C\u00e1c quy t\u1eafc to\u00e1n h\u1ecdc l\u1edbp 4 c\u1ef1c k\u1ef3 \u0111a d\u1ea1ng, tu\u1ef3 thu\u1ed9c v\u00e0o t\u1eebng ph\u1ea7n ki\u1ebfn th\u1ee9c \u0111\u1ec1u s\u1ebd c\u00f3 nh\u1eefng c\u00f4ng th\u1ee9c ri\u00eang. V\u1eady n\u00ean, n\u1ed9i dung b\u00e0i vi\u1ebft sau \u0111\u00e2y Shining Home &#8211; Gia \u0111\u00ecnh Anh Ng\u1eef t\u1ed5ng h\u1ee3p \u0111\u1ea7y \u0111\u1ee7 c\u00e1c quy t\u1eafc to\u00e1n l\u1edbp 4 \u0111\u1ec3 c\u00e1c em v\u00e0 ph\u1ee5 huynh tham kh\u1ea3o.<\/p>\n<p>                        View all<\/p>\n<h2 dir=\"ltr\"><span class=\"ez-toc-section\" id=\"Tong_hop_cac_quy_tac_toan_hoc_lop_4_day_du_nhat\"><\/span>T\u1ed5ng h\u1ee3p c\u00e1c quy t\u1eafc to\u00e1n h\u1ecdc l\u1edbp 4 \u0111\u1ea7y \u0111\u1ee7 nh\u1ea5t<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p dir=\"ltr\">Trong ch\u01b0\u01a1ng tr\u00ecnh to\u00e1n h\u1ecdc l\u1edbp 4, c\u00e1c em s\u1ebd ph\u1ea3i ghi nh\u1edb nh\u1eefng quy t\u1eafc, c\u00f4ng th\u1ee9c sau \u0111\u00e2y \u0111\u1ec3 h\u1ed7 tr\u1ee3 gi\u1ea3i b\u00e0i t\u1eadp v\u00e0 h\u1ecdc t\u1ed1t ki\u1ebfn th\u1ee9c t\u1ed1t h\u01a1n. V\u1eady n\u00ean, d\u01b0\u1edbi \u0111\u00e2y Shining Home &#8211; Gia \u0111\u00ecnh Anh Ng\u1eef s\u1ebd t\u1ed5ng h\u1ee3p c\u00e1c c\u00f4ng th\u1ee9c li\u00ean quan \u0111\u1ec3 c\u00e1c em c\u00f9ng nhau t\u00ecm hi\u1ec3u:<\/p>\n<h3 dir=\"ltr\"><span class=\"ez-toc-section\" id=\"On_tap_ve_so_tu_nhien\"><\/span>\u00d4n t\u1eadp v\u1ec1 s\u1ed1 t\u1ef1 nhi\u00ean<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p dir=\"ltr\">M\u1ed9t trong nh\u1eefng ph\u1ea7n ki\u1ebfn th\u1ee9c m\u00e0 b\u00e9 s\u1ebd \u0111\u01b0\u1ee3c h\u1ecdc trong ch\u01b0\u01a1ng tr\u00ecnh to\u00e1n l\u1edbp 4 \u0111\u1ea7u ti\u00ean ch\u00ednh l\u00e0 v\u1ec1 s\u1ed1 t\u1ef1 nhi\u00ean. \u0110\u00e2y l\u00e0 n\u1ed9i dung c\u01a1 b\u1ea3n \u0111\u1ec3 h\u1ed7 tr\u1ee3 tr\u1ebb c\u00f3 th\u1ec3 t\u00ednh to\u00e1n v\u00e0 h\u1ecdc t\u1eadp hi\u1ec7u qu\u1ea3. M\u1ed9t s\u1ed1 n\u1ed9i dung tr\u1ecdng t\u00e2m c\u1ee7a s\u1ed1 t\u1ef1 nhi\u00ean nh\u01b0 sau:<\/p>\n<p dir=\"ltr\"><img decoding=\"async\" class=\"lazyload\" src=\"https:\/\/external-content.duckduckgo.com\/iu\/?u=https:\/\/vnmedia2.monkeyuni.net\/upload\/web\/img\/cac-quy-tac-hoc-toan-lop-4-1.jpg\" alt=\"S\u1ed1 t\u1ef1 nhi\u00ean ch\u00ednh l\u00e0 ti\u1ec1n \u0111\u1ec1, n\u1ec1n t\u1ea3ng khi h\u1ecdc to\u00e1n c\u1ea7n n\u1eafm r\u00f5. (\u1ea2nh: S\u01b0u t\u1ea7m internet)\" width=\"100%\"><\/p>\n<h4 dir=\"ltr\"><span class=\"ez-toc-section\" id=\"_So_va_chu_so\"><\/span>* S\u1ed1 v\u00e0 ch\u1eef s\u1ed1<span class=\"ez-toc-section-end\"><\/span><\/h4>\n<p dir=\"ltr\">S\u1ed1 t\u1ef1 nhi\u00ean ch\u00ednh l\u00e0 c\u00e1c ch\u1eef s\u1ed1 \u0111\u01b0\u1ee3c th\u00e0nh l\u1eadp t\u1eeb 10 ch\u1eef s\u1ed1 c\u01a1 b\u1ea3n t\u1eeb 0, 1, 2, 3, 4, 5, 6, 7, 8, 9. T\u00ednh ch\u1ea5t c\u1ee7a nh\u1eefng s\u1ed1 t\u1ef1 nhi\u00ean n\u00e0y nh\u01b0 sau:<\/p>\n<ul>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">C\u00f3 t\u1ed5ng c\u1ed9ng 10 s\u1ed1 c\u00f3 1 ch\u1eef s\u1ed1 (0 \u2013 9)<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">C\u00f3 t\u1ed5ng c\u1ed9ng 90 s\u1ed1 c\u00f3 hai ch\u1eef s\u1ed1 (10 &#8211; 99)<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">C\u00f3 t\u1ed5ng c\u1ed9ng 900 s\u1ed1 c\u00f3 ba ch\u1eef s\u1ed1 (100 &#8211; 999)<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">C\u00f3 t\u1ed5ng c\u1ed9ng 9000 s\u1ed1 c\u00f3 b\u1ed1n ch\u1eef s\u1ed1 (1000 &#8211; 9999)<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">S\u1ed1 t\u1ef1 nhi\u00ean nh\u1ecf nh\u1ea5t l\u00e0 0 v\u00e0 kh\u00f4ng c\u00f3 s\u1ed1 t\u1ef1 nhi\u00ean l\u1edbn nh\u1ea5t.<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">C\u00e1c s\u1ed1 t\u1ef1 nhi\u00ean li\u00ean ti\u1ebfp nhau s\u1ebd h\u01a1n ho\u1eb7c k\u00e9m nhau m\u1ed9t \u0111\u01a1n v\u1ecb.<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">S\u1ed1 ch\u1eb5n trong d\u00e3y s\u1ed1 t\u1ef1 nhi\u00ean s\u1ebd c\u00f3 t\u1eadn c\u00f9ng l\u00e0 c\u00e1c s\u1ed1 0, 2, 4, 6, 8. Trong \u0111\u00f3, hai s\u1ed1 ch\u1eb5n g\u1ecdi l\u00e0 li\u00ean ti\u1ebfp nhau s\u1ebd h\u01a1n ho\u1eb7c k\u00e9m nhau 2 \u0111\u01a1n v\u1ecb.<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">S\u1ed1 l\u1ebb l\u00e0 nh\u1eefng ch\u1eef s\u1ed1 t\u1ef1 nhi\u00ean c\u00f3 t\u1eadn c\u00f9ng l\u00e0 3, 5, 7, 9. Hai s\u1ed1 l\u1ebb g\u1ecdi l\u00e0 li\u00ean ti\u1ebfp nhau s\u1ebd h\u01a1n ho\u1eb7c k\u00e9m nhau 2 \u0111\u01a1n v\u1ecb.<\/p>\n<\/li>\n<\/ul>\n<h4 dir=\"ltr\"><span class=\"ez-toc-section\" id=\"_Hang_va_lop\"><\/span>* H\u00e0ng v\u00e0 l\u1edbp<span class=\"ez-toc-section-end\"><\/span><\/h4>\n<p dir=\"ltr\">H\u00e0ng v\u00e0 l\u1edbp to\u00e1n l\u1edbp 4 ch\u00ednh l\u00e0 ki\u1ebfn th\u1ee9c tr\u1ecdng t\u00e2m \u0111\u1ec3 h\u1ed7 tr\u1ee3 b\u00e9 x\u00e1c \u0111\u1ecbnh \u0111\u01b0\u1ee3c gi\u00e1 tr\u1ecb c\u1ee7a s\u1ed1 t\u1ef1 nhi\u00ean ch\u00ednh x\u00e1c. C\u1ee5 th\u1ec3:<\/p>\n<ul>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">H\u00e0ng \u0111\u01a1n tr\u0103m, h\u00e0ng ch\u1ee5c, h\u00e0ng \u0111\u01a1n v\u1ecb s\u1ebd t\u1ea1o th\u00e0nh l\u1edbp \u0111\u01a1n v\u1ecb<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">H\u00e0ng tr\u0103m ngh\u00ecn, h\u00e0ng ch\u1ee5c ngh\u00ecn, h\u00e0ng ngh\u00ecn s\u1ebd t\u1ea1o th\u00e0nh l\u1edbp ngh\u00ecn.<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">\u0110\u1ec3 hi\u1ec3u \u0111\u01a1n gi\u1ea3n h\u01a1n, m\u1ecdi ng\u01b0\u1eddi c\u00f3 th\u1ec3 tham kh\u1ea3o b\u1ea3ng h\u00e0ng v\u00e0 l\u1edbp sau:<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">\u0110\u1ec3 gi\u1ea3i \u0111\u01b0\u1ee3c b\u00e0i t\u1eadp h\u00e0ng v\u00e0 l\u1edbp to\u00e1n l\u1edbp 4, c\u00e1c em c\u1ea7n ch\u00fa \u00fd nh\u1eefng v\u1ea5n \u0111\u1ec1 sau:<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">C\u00e1ch \u0111\u1ecdc: C\u00e1c em s\u1ebd \u0111\u1ecdc s\u1ed1 t\u1ef1 nhi\u00ean theo th\u1ee9 t\u1ef1 t\u1eeb tr\u00e1i qua ph\u1ea3i ho\u1eb7c t\u1eeb cao \u0111\u1ebfn th\u1ea5p.<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">C\u00e1c ch\u1eef s\u1ed1 t\u1eeb ph\u1ea3i qua tr\u00e1i l\u1ea7n l\u01b0\u1ee3t s\u1ebd l\u00e0 c\u00e1c h\u00e0ng \u0111\u01a1n v\u1ecb, h\u00e0ng ch\u1ee5c, h\u00e0ng tr\u0103m, h\u00e0ng ngh\u00ecn, h\u00e0ng ch\u1ee5c ngh\u00ecn, h\u00e0ng tr\u0103m ngh\u00ecn\u2026<\/p>\n<\/li>\n<\/ul>\n<h3 dir=\"ltr\"><span class=\"ez-toc-section\" id=\"Day_so\"><\/span>D\u00e3y s\u1ed1<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p dir=\"ltr\">D\u1ef1a theo s\u1ed1 t\u1ef1 nhi\u00ean, c\u00e1c d\u00e3y s\u1ed1 s\u1ebd \u0111\u01b0\u1ee3c s\u1eafp x\u1ebfp theo th\u1ee9 t\u1ef1 t\u1eeb nh\u1ecf \u0111\u1ebfn l\u1edbn nh\u01b0 sau: 0; 1; 2; 3; 4; 5; 6; 7; 8; 9; 10;\u2026<\/p>\n<p dir=\"ltr\">M\u1ed9t s\u1ed1 quy t\u1eafc c\u1ee7a m\u1ed9t d\u00e3y s\u1ed1 t\u1ef1 nhi\u00ean to\u00e1n l\u1edbp 4 m\u00e0 b\u00e9 c\u1ea7n n\u1eafm r\u00f5:<\/p>\n<ul>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">N\u1ebfu d\u00e3y s\u1ed1 li\u00ean ti\u1ebfp b\u1eaft \u0111\u1ea7u ch\u1ed7 ch\u1eb5n, k\u1ebft th\u00fac s\u1ed1 l\u1ebb v\u00e0 ng\u01b0\u1ee3c l\u1ea1i th\u00ec s\u1ed1 l\u01b0\u1ee3ng s\u1ed1 ch\u1eb5n s\u1ebd b\u1eb1ng s\u1ed1 l\u1ebb.<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">N\u1ebfu m\u1ed9t d\u00e3y s\u1ed1 li\u00ean ti\u1ebfp b\u1eaft \u0111\u1ea7u l\u00e0 s\u1ed1 ch\u1eb5n, k\u1ebft th\u00fac s\u1ed1 ch\u1eb5n th\u00ec s\u1ed1 l\u01b0\u1ee3ng s\u1ed1 ch\u1eb5n nhi\u1ec1u h\u01a1n s\u1ed1 l\u01b0\u1ee3ng s\u1ed1 l\u1ebb l\u00e0 1.<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">N\u1ebfu m\u1ed9t d\u00e3y s\u1ed1 li\u00ean ti\u1ebfp b\u1eaft \u0111\u1ea7u l\u00e0 s\u1ed1 l\u1ebb, k\u1ebft th\u00fac s\u1ed1 l\u1ebb th\u00ec s\u1ed1 l\u01b0\u1ee3ng s\u1ed1 l\u1ebb nhi\u1ec1u h\u01a1n s\u1ed1 l\u01b0\u1ee3ng s\u1ed1 ch\u1eb5n l\u00e0 1.<\/p>\n<\/li>\n<\/ul>\n<p dir=\"ltr\">Trong ph\u1ea7n d\u00e3y s\u1ed1 c\u00f3 th\u00eam thu\u1eadt ng\u1eef \u201cd\u00e3y s\u1ed1 c\u00e1ch \u0111\u1ec1u\u201d. N\u00ean \u0111\u1ec3 t\u00ednh \u0111\u01b0\u1ee3c c\u00e1c s\u1ed1 h\u1ea1ng c\u1ee7a d\u00e3y s\u1ed1 n\u00e0y ta c\u00f3 c\u00f4ng th\u1ee9c:\u00a0<\/p>\n<p dir=\"ltr\" style=\"text-align: center\">S\u1ed1 s\u1ed1 h\u1ea1ng = (s\u1ed1 h\u1ea1ng cu\u1ed1i \u2013 s\u1ed1 h\u1ea1ng \u0111\u1ea7u) : d + 1<\/p>\n<p dir=\"ltr\" style=\"text-align: center\">T\u1ed5ng = [ (s\u1ed1 \u0111\u1ea7u + s\u1ed1 cu\u1ed1i) x s\u1ed1 s\u1ed1 h\u1ea1ng] : 2<\/p>\n<p dir=\"ltr\"><em>V\u00ed d\u1ee5 1: T\u00ednh s\u1ed1 s\u1ed1 h\u1ea1ng c\u1ee7a d\u00e3y s\u1ed1 2, 4, 6, 8\u2026 10, 12.<\/em><\/p>\n<p dir=\"ltr\"><em>H\u01b0\u1edbng d\u1eabn gi\u1ea3i:<\/em><\/p>\n<p dir=\"ltr\"><em>Ta c\u00f3 4 \u2013 2 = 2; 6 \u2013 4 = 2. N\u00ean \u0111\u00e2y \u0111\u01b0\u1ee3c xem l\u00e0 d\u00e3y s\u1ed1 c\u00e1ch \u0111\u1ec1u.<\/em><\/p>\n<p dir=\"ltr\"><em>Suy ra ta c\u00f3 s\u1ed1 s\u1ed1 h\u1ea1ng c\u1ee7a d\u00e3y c\u00e1ch \u0111\u1ec1u tr\u00ean: (12 \u2013 2) : 2 +1 = 6<\/em><\/p>\n<p dir=\"ltr\"><em>V\u00ed d\u1ee5 2: T\u00ednh t\u1ed5ng c\u1ee7a d\u00e3y s\u1ed1: 2, 4, 6, 8\u2026 10, 12.<\/em><\/p>\n<p dir=\"ltr\"><em>T\u1ed5ng c\u1ee7a d\u00e3y s\u1ed1 c\u00e1ch \u0111\u1ec1u tr\u00ean =\u00a0 [(12 + 2) x 6] : 2 = 42.<\/em><\/p>\n<h3 dir=\"ltr\"><span class=\"ez-toc-section\" id=\"Phep_cong\"><\/span>Ph\u00e9p c\u1ed9ng<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p dir=\"ltr\">Ph\u00e9p c\u1ed9ng l\u00e0 ph\u00e9p t\u00ednh c\u01a1 b\u1ea3n trong to\u00e1n h\u1ecdc, d\u00f9ng \u0111\u1ec3 t\u00ednh t\u1ed5ng c\u00e1c \u0111\u1ea1i l\u01b0\u1ee3ng hay s\u1ed1 h\u00e0ng v\u1edbi nhau.<\/p>\n<p dir=\"ltr\">K\u00fd hi\u1ec7u:\u00a0 \u201c+\u201d.<\/p>\n<p dir=\"ltr\">Ta c\u00f3: a + b = c<\/p>\n<p dir=\"ltr\">Trong \u0111\u00f3: a v\u00e0 b l\u00e0 c\u00e1c s\u1ed1 h\u1ea1ng trong t\u1ed5ng, c l\u00e0 t\u1ed5ng c\u1ee7a ph\u00e9p to\u00e1n c\u1ed9ng.<\/p>\n<p dir=\"ltr\">M\u1ed9t s\u1ed1 t\u00ednh ch\u1ea5t c\u1ee7a ph\u00e9p c\u1ed9ng c\u00e1c b\u00e9 c\u1ea7n n\u1eafm r\u00f5:<\/p>\n<ul>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">T\u00ednh ch\u1ea5t giao ho\u00e0n: Trong ph\u00e9p t\u00ednh c\u1ed9ng, khi \u0111\u1ed5i ch\u1ed7 c\u00e1c s\u1ed1 h\u1ea1ng trong m\u1ed9t t\u1ed5ng th\u00ec t\u1ed5ng kh\u00f4ng thay \u0111\u1ed5i. \u2192 a + b = b + a<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">T\u00ednh ch\u1ea5t k\u1ebft h\u1ee3p: Trong m\u1ed9t ph\u00e9p t\u00ednh c\u1ed9ng, khi c\u1ed9ng t\u1ed5ng hai s\u1ed1 v\u1edbi m\u1ed9t s\u1ed1 th\u1ee9 ba, ta c\u00f3 th\u1ec3 c\u1ed9ng s\u1ed1 th\u1ee9 nh\u1ea5t v\u1edbi t\u1ed5ng c\u1ee7a s\u1ed1 th\u1ee9 hai v\u00e0 s\u1ed1 th\u1ee9 ba. \u2192 (a + b) + c = a + (b + c)<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">T\u00ednh ch\u1ea5t c\u1ed9ng v\u1edbi 0: B\u1ea5t c\u1ee9 s\u1ed1 n\u00e0o c\u1ed9ng v\u1edbi 0 th\u00ec c\u0169ng b\u1eb1ng ch\u00ednh n\u00f3. \u2192 a + 0 = 0 + a = a<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">Trong m\u1ed9t t\u1ed5ng c\u00f3 c\u00e1c s\u1ed1 h\u1ea1ng l\u1ebb l\u00e0 m\u1ed9t s\u1ed1 l\u1ebb th\u00ec t\u1ed5ng \u0111\u00f3 l\u00e0 m\u1ed9t s\u1ed1 l\u1ebb.<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">Trong m\u1ed9t t\u1ed5ng c\u00f3 c\u00e1c s\u1ed1 h\u1ea1ng l\u1ebb l\u00e0 ch\u1eb5n th\u00ec t\u1ed5ng \u0111\u00f3 l\u00e0 m\u1ed9t s\u1ed1 ch\u1eb5n.<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">T\u1ed5ng c\u1ee7a c\u00e1c s\u1ed1 h\u1ea1ng ch\u1eb5n l\u00e0 m\u1ed9t s\u1ed1 ch\u1eb5n.<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">T\u1ed5ng c\u1ee7a m\u1ed9t s\u1ed1 h\u1ea1ng l\u1ebb v\u00e0 m\u1ed9t s\u1ed1 h\u1ea1ng ch\u1eb5n l\u00e0 m\u1ed9t s\u1ed1 l\u1ebb.<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">T\u1ed5ng c\u1ee7a hai s\u1ed1 t\u1ef1 nhi\u00ean li\u00ean ti\u1ebfp l\u00e0 m\u1ed9t s\u1ed1 h\u1ea1ng l\u1ebb.<\/p>\n<\/li>\n<\/ul>\n<p dir=\"ltr\"><img decoding=\"async\" class=\"lazyload\" src=\"https:\/\/external-content.duckduckgo.com\/iu\/?u=https:\/\/vnmedia2.monkeyuni.net\/upload\/web\/img\/cac-quy-tac-hoc-toan-lop-4-2.jpg\" alt=\"C\u1ed9ng tr\u1eeb nh\u00e2n chia l\u00e0 4 ph\u00e9p t\u00ednh quan tr\u1ecdng trong to\u00e1n h\u1ecdc. (\u1ea2nh: S\u01b0u t\u1ea7m internet)\" width=\"100%\"><\/p>\n<h3 dir=\"ltr\"><span class=\"ez-toc-section\" id=\"Phep_tru\"><\/span>Ph\u00e9p tr\u1eeb<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p dir=\"ltr\">Ph\u00e9p tr\u1eeb l\u00e0 ph\u00e9p t\u00ednh gi\u1ea3m b\u1edbt s\u1ed1 ph\u1ea7n t\u1eeb t\u1eeb m\u1ed9t con s\u1ed1 n\u00e0o \u0111\u00f3 \u0111\u1ec3 c\u00f3 \u0111\u01b0\u1ee3c k\u1ebft qu\u1ea3 ch\u00ednh x\u00e1c.<\/p>\n<p dir=\"ltr\">K\u00fd hi\u1ec7u: \u201c-\u201d.<\/p>\n<p dir=\"ltr\">Ta c\u00f3: a \u2013 b = c<\/p>\n<p dir=\"ltr\">Trong \u0111\u00f3, ta c\u00f3 a l\u00e0 s\u1ed1 b\u1ecb tr\u1eeb, b l\u00e0 s\u1ed1 tr\u1eeb, c l\u00e0 hi\u1ec7u c\u1ee7a ph\u00e9p tr\u1eeb.<\/p>\n<p dir=\"ltr\">\u0110\u1ec3 th\u1ef1c hi\u1ec7n \u0111\u01b0\u1ee3c ph\u00e9p t\u00ednh tr\u1eeb c\u00e1c s\u1ed1 t\u1ef1 nhi\u00ean, ta c\u1ea7n n\u1eafm r\u00f5 c\u00e1c \u0111i\u1ec1u ki\u1ec7n sau:<\/p>\n<ul>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">S\u1ed1 b\u1ecb tr\u1eeb trong ph\u00e9p t\u00ednh ph\u1ea3i lu\u00f4n lu\u00f4n l\u1edbn h\u01a1n ho\u1eb7c b\u1eb1ng s\u1ed1 tr\u1eeb.<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">Th\u1ef1c hi\u1ec7n ph\u00e9p tr\u1eeb theo th\u1ee9 t\u1ef1 t\u1eeb tr\u00e1i sang ph\u1ea3i.<\/p>\n<\/li>\n<\/ul>\n<p dir=\"ltr\">M\u1ed9t s\u1ed1 t\u00ednh ch\u1ea5t trong ph\u00e9p tr\u1eeb:<\/p>\n<ul>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">Tr\u1eeb \u0111i s\u1ed1 0: B\u1ea5t k\u1ef3 m\u1ed9t s\u1ed1 t\u1ef1 nhi\u00ean n\u00e0o tr\u1eeb \u0111i 0 th\u00ec v\u1eabn b\u1eb1ng ch\u00ednh n\u00f3. \u2192 a \u2013 0 = a<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">Tr\u1eeb \u0111i ch\u00ednh n\u00f3: B\u1ea5t k\u1ef3 m\u1ed9t s\u1ed1 t\u1ef1 nhi\u00ean n\u00e0o khi tr\u1eeb \u0111i ch\u00ednh n\u00f3 th\u00ec s\u1ebd b\u1eb1ng 0. \u2192 a \u2013 a = 0<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">Tr\u1eeb \u0111i m\u1ed9t t\u1ed5ng: Khi th\u1ef1c hi\u1ec7n ph\u00e9p tr\u1eeb c\u1ee7a m\u1ed9t s\u1ed1 t\u1ef1 nhi\u00ean cho m\u1ed9t t\u1ed5ng, ta c\u00f3 th\u1ec3 l\u1ea5y s\u1ed1 \u0111\u00f3 tr\u1eeb cho t\u1eebng s\u1ed1 h\u1ea1ng c\u1ee7a t\u1ed5ng \u0111\u00f3. \u2192 a \u2013 (b + c) = a \u2013 b \u2013 c = a \u2013 c \u2013 b.<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">Tr\u1eeb \u0111i m\u1ed9t hi\u1ec7u: Khi th\u1ef1c hi\u1ec7n ph\u00e9p tr\u1eeb c\u1ee7a m\u1ed9t s\u1ed1 t\u1ef1 nhi\u00ean cho m\u1ed9t hi\u1ec7u, ta c\u00f3 th\u1ec3 l\u1ea5y s\u1ed1 \u0111\u00f3 tr\u1eeb cho s\u1ed1 b\u1ecb tr\u1eeb r\u1ed3i c\u1ed9ng v\u1edbi s\u1ed1 tr\u1eeb. \u2192\u00a0 a \u2013 (b \u2013 c) = a \u2013 b + c = a + c \u2013 b.<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">Trong m\u1ed9t ph\u00e9p tr\u1eeb, n\u1ebfu s\u1ed1 b\u1ecb tr\u1eeb v\u00e0 s\u1ed1 tr\u1eeb c\u00f9ng t\u0103ng (ho\u1eb7c c\u00f9ng gi\u1ea3m) n \u0111\u01a1n v\u1ecb th\u00ec hi\u1ec7u c\u1ee7a ch\u00fang kh\u00f4ng \u0111\u1ed5i.<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">Trong m\u1ed9t ph\u00e9p tr\u1eeb, n\u1ebfu s\u1ed1 b\u1ecb tr\u1eeb \u0111\u01b0\u1ee3c g\u1ea5p l\u00ean n l\u1ea7n v\u00e0 gi\u1eef nguy\u00ean s\u1ed1 tr\u1eeb th\u00ec hi\u1ec7u \u0111\u01b0\u1ee3c t\u0103ng th\u00eam m\u1ed9t s\u1ed1 \u0111\u00fang b\u1eb1ng (n \u2013 1) l\u1ea7n s\u1ed1 b\u1ecb tr\u1eeb (n &gt; 1).<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">Trong m\u1ed9t ph\u00e9p tr\u1eeb, n\u1ebfu s\u1ed1 b\u1ecb tr\u1eeb gi\u1eef nguy\u00ean, s\u1ed1 tr\u1eeb \u0111\u01b0\u1ee3c g\u1ea5p l\u00ean n l\u1ea7n th\u00ec hi\u1ec7u b\u1ecb gi\u1ea3m \u0111i (n \u2013 1) l\u1ea7n s\u1ed1 tr\u1eeb\u00a0 (n &gt; 1).<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">Trong m\u1ed9t ph\u00e9p tr\u1eeb, n\u1ebfu s\u1ed1 b\u1ecb tr\u1eeb \u0111\u01b0\u1ee3c t\u0103ng th\u00eam n \u0111\u01a1n v\u1ecb, s\u1ed1 tr\u1eeb gi\u1eef nguy\u00ean th\u00ec hi\u1ec7u t\u0103ng l\u00ean n \u0111\u01a1n v\u1ecb.<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">Trong m\u1ed9t ph\u00e9p tr\u1eeb, n\u1ebfu s\u1ed1 b\u1ecb tr\u1eeb t\u0103ng l\u00ean n \u0111\u01a1n v\u1ecb, s\u1ed1 tr\u1eeb gi\u1eef nguy\u00ean th\u00ec hi\u1ec7u gi\u1ea3m \u0111i n \u0111\u01a1n v\u1ecb.<\/p>\n<\/li>\n<\/ul>\n<h3 dir=\"ltr\"><span class=\"ez-toc-section\" id=\"Cac_quy_tac_toan_hoc_lop_4_ve_phep_nhan\"><\/span>C\u00e1c quy t\u1eafc to\u00e1n h\u1ecdc l\u1edbp 4 v\u1ec1 ph\u00e9p nh\u00e2n<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p dir=\"ltr\">Ph\u00e9p nh\u00e2n c\u0169ng l\u00e0 m\u1ed9t tr\u1ecdng 4 ph\u00e9p t\u00ednh c\u01a1 b\u1ea3n trong to\u00e1n h\u1ecdc, c\u00f9ng \u0111\u1ec3 t\u00ecm hai hay nhi\u1ec1u s\u1ed1 t\u1ef1 nhi\u00ean th\u00f4ng qua vi\u1ec7c c\u1ed9ng l\u1eb7p l\u1ea1i c\u00e1c s\u1ed1 \u0111\u00f3.<\/p>\n<p dir=\"ltr\">K\u00fd hi\u1ec7u: D\u1ea5u \u201cx\u201d ho\u1eb7c d\u1ea5u \u201c.\u201d.<\/p>\n<p dir=\"ltr\">Ta c\u00f3: a x b = c<\/p>\n<p dir=\"ltr\">Trong \u0111\u00f3: a, b g\u1ecdi l\u00e0 c\u00e1c th\u1eeba s\u1ed1 v\u00e0 c l\u00e0 t\u00edch c\u1ee7a c\u00e1c th\u1eeba s\u1ed1.<\/p>\n<p dir=\"ltr\">M\u1ed9t s\u1ed1 t\u00ednh ch\u1ea5t c\u1ee7a ph\u00e9p t\u00ednh nh\u00e2n:<\/p>\n<ul>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">T\u00ednh ch\u1ea5t giao ho\u00e1n: Khi ho\u00e0n \u0111\u1ed5i v\u1ecb tr\u00ed c\u00e1c th\u1eeba s\u1ed1 trong m\u1ed9t t\u00edch th\u00ec t\u00edch s\u1ebd kh\u00f4ng thay \u0111\u1ed5i. \u2192 a x b = b x a<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">T\u00ednh ch\u1ea5t k\u1ebft h\u1ee3p: Khi th\u1ef1c hi\u1ec7n ph\u00e9p nh\u00e2n hai s\u1ed1 t\u1ef1 nhi\u00ean v\u1edbi s\u1ed1 th\u1ee9 ba, ta c\u00f3 th\u1ec3 nh\u00e2n s\u1ed1 th\u1ee9 nh\u1ea5t v\u1edbi t\u00edch hai s\u1ed1 c\u00f2n l\u1ea1i. \u2192 (a x b) x c = a x (b x c)<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">T\u00ednh ch\u1ea5t nh\u00e2n v\u1edbi s\u1ed1 0: B\u1ea5t k\u1ef3 s\u1ed1 t\u1ef1 nhi\u00ean n\u00e0o nh\u00e2n v\u1edbi s\u1ed1 0 th\u00ec t\u00edch s\u1ebd b\u1eb1ng 0. \u2192 a x 0 = 0 x a = 0<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">T\u00ednh ch\u1ea5t nh\u00e2n v\u1edbi s\u1ed1 1: B\u1ea5t k\u1ef3 s\u1ed1 t\u1ef1 nhi\u00ean n\u00e0o khi nh\u00e2n v\u1edbi 1 th\u00ec c\u0169ng b\u1eb1ng ch\u00ednh n\u00f3. \u2192 a x 1 = 1 x a = a<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">Nh\u00e2n m\u1ed9t s\u1ed1 v\u1edbi m\u1ed9t t\u1ed5ng: Khi nh\u00e2n m\u1ed9t s\u1ed1 t\u1ef1 nhi\u00ean v\u1edbi m\u1ed9t t\u1ed5ng, ta c\u00f3 th\u1ec3 l\u1ea5y s\u1ed1 \u0111\u00f3 nh\u00e2n v\u1edbi t\u1eebng s\u1ed1 h\u1ea1ng c\u1ee7a t\u1ed5ng v\u00e0 c\u1ed9ng c\u00e1c k\u1ebft qu\u1ea3 v\u1edbi nhau. \u2192 a x (b + c) = a x b + a x c\u00a0<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">Nh\u00e2n m\u1ed9t s\u1ed1 v\u1edbi m\u1ed9t hi\u1ec7u: Khi nh\u00e2n m\u1ed9t s\u1ed1 t\u1ef1 nhi\u00ean v\u1edbi m\u1ed9t hi\u1ec7u, ta c\u00f3 th\u1ec3 l\u1ea5y s\u1ed1 \u0111\u00f3 nh\u00e2n v\u1edbi s\u1ed1 b\u1ecb tr\u1eeb v\u00e0 s\u1ed1 tr\u1eeb r\u1ed3i tr\u1eeb hai k\u1ebft qu\u1ea3 \u0111\u00f3 v\u1edbi nhau. \u2192 a x (b \u2013 c) = a x b \u2013 a x c<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">Trong m\u1ed9t t\u00edch n\u1ebfu m\u1ed9t th\u1eeba s\u1ed1 \u0111\u01b0\u1ee3c g\u1ea5p l\u00ean n l\u1ea7n \u0111\u1ed3ng th\u1eddi c\u00f3 m\u1ed9t th\u1eeba s\u1ed1 kh\u00e1c b\u1ecb gi\u1ea3m \u0111i n l\u1ea7n th\u00ec t\u00edch c\u1ee7a ph\u00e9p nh\u00e2n \u0111\u00f3 s\u1ebd kh\u00f4ng thay \u0111\u1ed5i.<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">Trong m\u1ed9t t\u00edch c\u00f3 m\u1ed9t th\u1eeba s\u1ed1 \u0111\u01b0\u1ee3c g\u1ea5p l\u00ean n l\u1ea7n, c\u00e1c th\u1eeba s\u1ed1 c\u00f2n l\u1ea1i gi\u1eef nguy\u00ean gi\u00e1 tr\u1ecb th\u00ec t\u00edch \u0111\u01b0\u1ee3c g\u1ea5p l\u00ean n l\u1ea7n v\u00e0 ng\u01b0\u1ee3c l\u1ea1i n\u1ebfu trong m\u1ed9t t\u00edch c\u00f3 m\u1ed9t th\u1eeba s\u1ed1 b\u1ecb gi\u1ea3m \u0111i n l\u1ea7n, c\u00e1c th\u1eeba s\u1ed1 c\u00f2n l\u1ea1i gi\u1eef nguy\u00ean th\u00ec t\u00edch \u0111\u00f3 c\u0169ng b\u1ecb gi\u1ea3m \u0111i n l\u1ea7n. (n &gt; 0)<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">Trong m\u1ed9t t\u00edch, n\u1ebfu m\u1ed9t th\u1eeba s\u1ed1 \u0111\u01b0\u1ee3c g\u1ea5p l\u00ean n l\u1ea7n, \u0111\u1ed3ng th\u1eddi m\u1ed9t th\u1eeba s\u1ed1 kh\u00e1c c\u0169ng \u0111\u01b0\u1ee3c g\u1ea5p l\u00ean m l\u1ea7n th\u00ec t\u00edch \u0111\u01b0\u1ee3c g\u1ea5p l\u00ean (m \u00d7 n) l\u1ea7n. Ng\u01b0\u1ee3c l\u1ea1i n\u1ebfu trong m\u1ed9t t\u00edch c\u00f3 m\u1ed9t th\u1eeba s\u1ed1 b\u1ecb gi\u1ea3m \u0111i m l\u1ea7n, m\u1ed9t th\u1eeba s\u1ed1 kh\u00e1c c\u0169ng b\u1ecb gi\u1ea3m \u0111i n l\u1ea7n th\u00ec t\u00edch \u0111\u00f3 b\u1ecb gi\u1ea3m \u0111i (m \u00d7 n) l\u1ea7n (m v\u00e0 n kh\u00e1c 0).<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">Trong m\u1ed9t t\u00edch, n\u1ebfu m\u1ed9t th\u1eeba s\u1ed1 \u0111\u01b0\u1ee3c t\u0103ng th\u00eam a \u0111\u01a1n v\u1ecb, c\u00e1c th\u1eeba s\u1ed1 c\u00f2n l\u1ea1i gi\u1eef nguy\u00ean th\u00ec t\u00edch \u0111\u01b0\u1ee3c t\u0103ng th\u00eam a l\u1ea7n t\u00edch c\u00e1c th\u1eeba s\u1ed1 c\u00f2n l\u1ea1i c\u1ee7a ph\u00e9p nh\u00e2n.<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">Trong m\u1ed9t t\u00edch, n\u1ebfu c\u00f3 \u00edt nh\u1ea5t m\u1ed9t th\u1eeba s\u1ed1 l\u00e0 s\u1ed1 ch\u1eb5n th\u00ec t\u00edch \u0111\u00f3 l\u00e0 s\u1ed1 ch\u1eb5n.<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">Trong m\u1ed9t t\u00edch, n\u1ebfu c\u00f3 \u00edt nh\u1ea5t m\u1ed9t th\u1eeba s\u1ed1 l\u00e0 s\u1ed1 tr\u00f2n ch\u1ee5c ho\u1eb7c \u00edt nh\u1ea5t m\u1ed9t th\u1eeba s\u1ed1 c\u00f3 ch\u1eef s\u1ed1 t\u1eadn c\u00f9ng l\u00e0 5 v\u00e0 c\u00f3 \u00edt nh\u1ea5t m\u1ed9t th\u1eeba s\u1ed1 ch\u1eb5n th\u00ec t\u00edch s\u1ebd c\u00f3 ch\u1eef s\u1ed1 t\u1eadn c\u00f9ng l\u00e0 0.<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">Trong m\u1ed9t t\u00edch c\u00e1c th\u1eeba s\u1ed1 \u0111\u1ec1u l\u1ebb v\u00e0 c\u00f3 \u00edt nh\u1ea5t m\u1ed9t th\u1eeba s\u1ed1 c\u00f3 ch\u1eef s\u1ed1 t\u1eadn c\u00f9ng l\u00e0 5 th\u00ec t\u00edch c\u00f3 t\u1eadn c\u00f9ng l\u00e0 5.<\/p>\n<\/li>\n<\/ul>\n<h3 dir=\"ltr\"><span class=\"ez-toc-section\" id=\"Phep_chia\"><\/span>Ph\u00e9p chia<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p dir=\"ltr\">Ph\u00e9p chia ch\u00ednh l\u00e0 ph\u00e9p t\u00ednh ng\u01b0\u1ee3c c\u1ee7a ph\u00e9p nh\u00e2n. N\u00ean khi chia c\u00e1c s\u1ed1 t\u1ef1 nhi\u00ean, k\u1ebft qu\u1ea3 s\u1ebd \u0111\u01b0\u1ee3c g\u1ecdi l\u00e0 th\u01b0\u01a1ng v\u00e0 s\u1ebd c\u00f3 hai tr\u01b0\u1eddng h\u1ee3p \u0111\u00f3 l\u00e0 ph\u00e9p chia h\u1ebft v\u00e0 ph\u00e9p chia c\u00f3 d\u01b0.<\/p>\n<p dir=\"ltr\">K\u00fd hi\u1ec7u: D\u1ea5u \u201c:\u201d ho\u1eb7c \u201c\/\u201d.<\/p>\n<p dir=\"ltr\">Ta c\u00f3: a : b = c<\/p>\n<p dir=\"ltr\">Trong \u0111\u00f3, ta c\u00f3 a l\u00e0 s\u1ed1 b\u1ecb chia, b l\u00e0 s\u1ed1 chia v\u00e0 c l\u00e0 th\u01b0\u01a1ng c\u1ee7a ph\u00e9p chia.<\/p>\n<p dir=\"ltr\">L\u01b0u \u00fd: S\u1ed1 chia b lu\u00f4n lu\u00f4n kh\u00e1c 0 th\u00ec ph\u00e9p chia m\u1edbi c\u00f3 ngh\u0129a.<\/p>\n<p dir=\"ltr\">M\u1ed9t s\u1ed1 t\u00ednh ch\u1ea5t c\u1ee7a ph\u00e9p chia c\u00e1c em c\u1ea7n ghi nh\u1edb:<\/p>\n<p dir=\"ltr\">Chia m\u1ed9t s\u1ed1 cho 1: B\u1ea5t k\u1ef3 m\u1ed9t s\u1ed1 t\u1ef1 nhi\u00ean n\u00e0o khi chia cho 1 th\u00ec v\u1eabn b\u1eb1ng ch\u00ednh n\u00f3.<\/p>\n<p dir=\"ltr\">\u2192 a : 1 = a\u00a0<\/p>\n<p dir=\"ltr\">Chia m\u1ed9t s\u1ed1 cho ch\u00ednh n\u00f3: B\u1ea5t k\u1ef3 s\u1ed1 t\u1ef1 nhi\u00ean n\u00e0o khi chia cho ch\u00ednh n\u00f3 th\u00ec s\u1ebd b\u1eb1ng 1.<\/p>\n<p dir=\"ltr\">\u2192 a : a = 1<\/p>\n<p dir=\"ltr\">S\u1ed1 0 chia cho m\u1ed9t s\u1ed1 t\u1ef1 nhi\u00ean: Khi s\u1ed1 0 chia cho m\u1ed9t s\u1ed1 t\u1ef1 nhi\u00ean kh\u00e1c 0 th\u00ec k\u1ebft qu\u1ea3 s\u1ebd b\u1eb1ng 0.<\/p>\n<p dir=\"ltr\">\u2192 0 : a = 0<\/p>\n<p dir=\"ltr\">M\u1ed9t t\u1ed5ng chia cho m\u1ed9t s\u1ed1 t\u1ef1 nhi\u00ean: Khi th\u1ef1c hi\u1ec7n ph\u00e9p chia m\u1ed9t t\u1ed5ng cho m\u1ed9t s\u1ed1 t\u1ef1 nhi\u00ean kh\u00e1c 0, ta l\u1ea5y t\u1eebng s\u1ed1 h\u1ea1ng c\u1ee7a t\u1ed5ng \u0111\u00f3 chia cho s\u1ed1 chia v\u00e0 c\u1ed9ng c\u00e1c k\u1ebft qu\u1ea3 l\u1ea1i v\u1edbi nhau. (Trong tr\u01b0\u1eddng h\u1ee3p c\u00e1c s\u1ed1 h\u1ea1ng \u0111\u00f3 \u0111\u1ec1u chia h\u1ebft cho s\u1ed1 chia).<\/p>\n<p dir=\"ltr\">\u2192 (a + b) : c = a : c + b : c<\/p>\n<p dir=\"ltr\">M\u1ed9t hi\u1ec7u chia cho m\u1ed9t s\u1ed1 t\u1ef1 nhi\u00ean: Khi th\u1ef1c hi\u1ec7n ph\u00e9p chia m\u1ed9t tr\u1eeb cho m\u1ed9t s\u1ed1 t\u1ef1 nhi\u00ean kh\u00e1c 0, ta l\u1ea5y t\u1eebng s\u1ed1 b\u1ecb tr\u1eeb v\u00e0 s\u1ed1 tr\u1eeb c\u1ee7a hi\u1ec7u \u0111\u00f3 chia cho s\u1ed1 chia v\u00e0 tr\u1eeb c\u00e1c k\u1ebft qu\u1ea3 l\u1ea1i v\u1edbi nhau. (Trong tr\u01b0\u1eddng h\u1ee3p s\u1ed1 b\u1ecb tr\u1eeb v\u00e0 s\u1ed1 tr\u1eeb \u0111\u00f3 \u0111\u1ec1u chia h\u1ebft cho s\u1ed1 chia).<\/p>\n<p dir=\"ltr\">\u2192 (a \u2013 b) : c = a : c \u2013 b : c<\/p>\n<p dir=\"ltr\">Chia m\u1ed9t s\u1ed1 cho m\u1ed9t t\u00edch: Khi chia m\u1ed9t s\u1ed1 t\u1ef1 nhi\u00ean cho m\u1ed9t t\u00edch, ta c\u00f3 th\u1ec3 chia s\u1ed1 \u0111\u00f3 cho m\u1ed9t th\u1eeba s\u1ed1, r\u1ed3i l\u1ea5y k\u1ebft qu\u1ea3 v\u1eeba t\u00ecm chia ti\u1ebfp cho th\u1eeba s\u1ed1 kia.<\/p>\n<p dir=\"ltr\">\u2192 a : (b x c) = a : b : c = a : c : b<\/p>\n<p dir=\"ltr\">Chia m\u1ed9t t\u00edch cho m\u1ed9t s\u1ed1 t\u1ef1 nhi\u00ean: Khi chia m\u1ed9t t\u00edch cho m\u1ed9t s\u1ed1 t\u1ef1 nhi\u00ean, ta c\u00f3 th\u1ec3 l\u1ea5y m\u1ed9t th\u1eeba s\u1ed1 chia cho s\u1ed1 chia (tr\u01b0\u1eddng h\u1ee3p chia h\u1ebft), r\u1ed3i l\u1ea5y k\u1ebft qu\u1ea3 v\u1eeba t\u00ecm nh\u00e2n v\u1edbi th\u1eeba s\u1ed1 kia.<\/p>\n<p dir=\"ltr\">\u2192 (a x b) : c = a : c x b = b : c x a<\/p>\n<h3 dir=\"ltr\"><span class=\"ez-toc-section\" id=\"Tinh_chat_chia_het_cua_day_so_tu_nhien\"><\/span>T\u00ednh ch\u1ea5t chia h\u1ebft c\u1ee7a d\u00e3y s\u1ed1 t\u1ef1 nhi\u00ean<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p dir=\"ltr\">B\u00ean c\u1ea1nh vi\u1ec7c th\u00e0nh th\u1ea1o c\u00e1c ph\u00e9p t\u00ednh, c\u00e1c em c\u1ea7n ph\u1ea3i n\u1eafm r\u00f5 d\u1ea5u hi\u1ec7u ph\u00e9p chia h\u1ebft cho c\u00e1c s\u1ed1 2, 3, 5, 9 \u0111\u1ec3 t\u00ednh to\u00e1n nhanh h\u01a1n. C\u1ee5 th\u1ec3:<\/p>\n<p dir=\"ltr\">C\u00e1c s\u1ed1 t\u1ef1 nhi\u00ean c\u00f3 ch\u1eef s\u1ed1 t\u1eadn c\u00f9ng l\u00e0 0, 2, 4, 6, 8 th\u00ec s\u1ed1 \u0111\u00f3 chia h\u1ebft cho 2.<\/p>\n<p dir=\"ltr\"><em>V\u00ed d\u1ee5: C\u00e1c s\u1ed1 2, 24, 48, 66,\u2026 \u0111\u1ec1u chia h\u1ebft cho 2 v\u00ec ch\u00fang \u0111\u1ec1u l\u00e0 s\u1ed1 c\u00f3 t\u1eadn c\u00f9ng l\u00e0 c\u00e1c s\u1ed1 2, 4, 6, 8.<\/em><\/p>\n<p dir=\"ltr\">C\u00e1c s\u1ed1 t\u1ef1 nhi\u00ean c\u00f3 t\u1ed5ng c\u00e1c ch\u1eef s\u1ed1 chia h\u1ebft cho 3 th\u00ec s\u1ed1 \u0111\u00f3 s\u1ebd chia h\u1ebft cho 3.<\/p>\n<p dir=\"ltr\"><em>V\u00ed d\u1ee5: 252 chia h\u1ebft cho 3 v\u00ec trong s\u1ed1 252 c\u00f3 t\u1ed5ng c\u00e1c ch\u1eef s\u1ed1 2 + 5 + 2 = 9 chia h\u1ebft cho 3.<\/em><\/p>\n<p dir=\"ltr\">C\u00e1c s\u1ed1 t\u1ef1 nhi\u00ean c\u00f3 ch\u1eef s\u1ed1 t\u1eadn c\u00f9ng l\u00e0 0 ho\u1eb7c 5 th\u00ec s\u1ed1 \u0111\u00f3 chia h\u1ebft cho 5.<\/p>\n<p dir=\"ltr\"><em>V\u00ed d\u1ee5: 205, 2005, 4000 chia h\u1ebft cho 5 v\u00ec c\u00e1c s\u1ed1 tr\u00ean \u0111\u1ec1u c\u00f3 ch\u1eef s\u1ed1 t\u1eadn c\u00f9ng l\u00e0 0 v\u00e0 5.<\/em><\/p>\n<p dir=\"ltr\">C\u00e1c s\u1ed1 t\u1ef1 nhi\u00ean c\u00f3 t\u1ed5ng c\u00e1c ch\u1eef s\u1ed1 chia h\u1ebft cho 9 th\u00ec s\u1ed1 \u0111\u00f3 chia h\u1ebft cho 9.<\/p>\n<p dir=\"ltr\"><em>V\u00ed d\u1ee5: 8766 chia h\u1ebft cho 9 v\u00ec trong s\u1ed1 657 c\u00f3 t\u1ed5ng c\u00e1c ch\u1eef s\u1ed1 8 + 7 + 6 + 6= 21 chia h\u1ebft cho 9.<\/em><\/p>\n<h3 dir=\"ltr\"><span class=\"ez-toc-section\" id=\"Toan_Trung_binh_cong\"><\/span>To\u00e1n Trung b\u00ecnh c\u1ed9ng<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p dir=\"ltr\">\u0110\u1ec3 t\u00ecm \u0111\u01b0\u1ee3c trung b\u00ecnh c\u1ed9ng (TBC) c\u1ee7a d\u00e3y s\u1ed1 t\u1ef1 nhi\u00ean, ta s\u1ebd t\u00ednh t\u1ed5ng c\u1ee7a ch\u00fang r\u1ed3i chia cho c\u00e1c s\u1ed1 h\u1ea1ng. C\u1ee5 th\u1ec3:<\/p>\n<p dir=\"ltr\" style=\"text-align: center\">TBC = t\u1ed5ng c\u00e1c s\u1ed1 h\u1ea1ng : s\u1ed1 c\u00e1c s\u1ed1 h\u1ea1ng<\/p>\n<p dir=\"ltr\">Ng\u01b0\u1ee3c l\u1ea1i, \u0111\u1ec3 t\u00ecm t\u1ed5ng c\u00e1c s\u1ed1 t\u1ef1 nhi\u00ean, ta l\u1ea5y TBC nh\u00e2n v\u1edbi s\u1ed1 c\u00e1c s\u1ed1 h\u1ea1ng.<\/p>\n<p dir=\"ltr\"><em>V\u00ed d\u1ee5: T\u00ecm s\u1ed1 trung b\u00ecnh c\u1ed9ng c\u1ee7a c\u00e1c s\u1ed1 sau: 3, 5, 7, 9, 11, 13, 15<\/em><\/p>\n<p dir=\"ltr\"><em>\u2192 TBC = (3 + 5 + 7 + 9 + 11 + 13 + 15) : 7 = 9<\/em><\/p>\n<p dir=\"ltr\"><img decoding=\"async\" class=\"lazyload\" src=\"https:\/\/external-content.duckduckgo.com\/iu\/?u=https:\/\/vnmedia2.monkeyuni.net\/upload\/web\/img\/cac-quy-tac-hoc-toan-lop-4-3.jpg\" alt=\"Trung b\u00ecnh c\u1ed9ng l\u00e0 ph\u1ea7n ki\u1ebfn th\u1ee9c xuy\u00ean su\u1ed1t ch\u01b0\u01a1ng tr\u00ecnh to\u00e1n l\u1edbp 4. (\u1ea2nh: S\u01b0u t\u1ea7m internet)\" width=\"100%\"><\/p>\n<table style=\"border-collapse: collapse;width: 100%;background-color: #fbeeb8\" border=\"1\">\n<tr>\n<td style=\"width: 98.5189%\">\n<p style=\"text-align: center\">X\u00c2Y D\u1ef0NG N\u1ec0N T\u1ea2NG TO\u00c1N H\u1eccC, PH\u00c1T TRI\u1ec2N T\u01af DUY N\u0102NG L\u1ef0C H\u1eccC TO\u00c1N V\u00c0 PH\u00c1T TRI\u1ec2N NG\u00d4N NG\u1eee CHO TR\u1eba C\u00d9NG V\u1edaI MONKEY MATH CH\u1ec8 V\u1edaI 2K\/NG\u00c0Y.<\/p>\n<p style=\"text-align: center\">\u00a0<\/p>\n<p><img decoding=\"async\" style=\"margin-left: auto;margin-right: auto\" class=\"lazyload\" src=\"https:\/\/external-content.duckduckgo.com\/iu\/?u=https:\/\/vnmedia2.monkeyuni.net\/upload\/web\/img\/timhieungay.png\" alt=\"\" width=\"200\"><\/p>\n<\/td>\n<\/tr>\n<\/table>\n<h3 dir=\"ltr\"><span class=\"ez-toc-section\" id=\"Cac_quy_tac_toan_hoc_lop_4_ve_toan_ti_le_thuan\"><\/span>C\u00e1c quy t\u1eafc to\u00e1n h\u1ecdc l\u1edbp 4 v\u1ec1 to\u00e1n t\u1ec9 l\u1ec7 thu\u1eadn<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p dir=\"ltr\">Trong to\u00e1n h\u1ecdc, hai \u0111\u1ea1i l\u01b0\u1ee3ng t\u1ec9 l\u1ec7 thu\u1eadn ch\u00ednh l\u00e0 khi m\u1ed9t \u0111\u1ea1i l\u01b0\u1ee3ng t\u0103ng ho\u1eb7c gi\u1ea3m bao nhi\u00eau l\u1ea7n th\u00ec \u0111\u1ea1i l\u01b0\u1ee3ng c\u00f2n l\u1ea1i c\u0169ng s\u1ebd t\u0103ng ho\u1eb7c gi\u1ea3m t\u1eebng \u0111\u00f3 l\u1ea7n.<\/p>\n<p dir=\"ltr\"><em>V\u00ed d\u1ee5: M\u1ed9t \u00f4 t\u00f4 trong hai gi\u1edd \u0111i \u0111\u01b0\u1ee3c 90km. H\u1ecfi trong 4 gi\u1edd \u00f4 t\u00f4 \u0111\u00f3 \u0111i \u0111\u01b0\u1ee3c bao nhi\u00eau ki- l\u00f4- m\u00e9t?<\/em><\/p>\n<p dir=\"ltr\"><em>T\u00f3m t\u1eaft:<\/em><\/p>\n<p dir=\"ltr\"><em>2 gi\u1edd: 90 km<\/em><\/p>\n<p dir=\"ltr\"><em>4 gi\u1edd: \u2026 km?<\/em><\/p>\n<p dir=\"ltr\"><em>B\u00e0i gi\u1ea3i<\/em><\/p>\n<p dir=\"ltr\"><em>C\u00e1ch 1:<\/em><\/p>\n<p dir=\"ltr\"><em>Trong m\u1ed9t gi\u1edd \u00f4 t\u00f4 \u0111i \u0111\u01b0\u1ee3c l\u00e0:<\/em><\/p>\n<p dir=\"ltr\"><em>90 : 2 = 45 (km) (*)<\/em><\/p>\n<p dir=\"ltr\"><em>Trong 4 gi\u1edd \u00f4 t\u00f4 \u0111i \u0111\u01b0\u1ee3c l\u00e0:<\/em><\/p>\n<p dir=\"ltr\"><em>45 \u00d7 4 = 180 (km)<\/em><\/p>\n<p dir=\"ltr\"><em>\u0110\u00e1p s\u1ed1: 180 km<\/em><\/p>\n<p dir=\"ltr\"><em>C\u00e1ch 2:<\/em><\/p>\n<p dir=\"ltr\"><em>4 gi\u1edd g\u1ea5p 2 gi\u1edd s\u1ed1 l\u1ea7n l\u00e0:<\/em><\/p>\n<p dir=\"ltr\"><em>4 : 2 = 2 (l\u1ea7n) (**)<\/em><\/p>\n<p dir=\"ltr\"><em>Trong 4 gi\u1edd \u00f4 t\u00f4 \u0111i \u0111\u01b0\u1ee3c l\u00e0:<\/em><\/p>\n<p dir=\"ltr\"><em>90 \u00d7 2 = 180 (km)<\/em><\/p>\n<p dir=\"ltr\"><em>\u0110\u00e1p s\u1ed1: 180 km<\/em><\/p>\n<h3 dir=\"ltr\"><span class=\"ez-toc-section\" id=\"Toan_ti_le_nghich\"><\/span>To\u00e1n t\u1ec9 l\u1ec7 ngh\u1ecbch<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p dir=\"ltr\">Ng\u01b0\u1ee3c l\u1ea1i v\u1edbi to\u00e1n t\u1ec9 l\u1ec7 thu\u1eadn, n\u1ebfu hai \u0111\u1ea1i l\u01b0\u1ee3ng t\u1ec9 l\u1ec7 ngh\u1ecbch l\u00e0 khi m\u1ed9t \u0111\u1ea1i l\u01b0\u1ee3ng t\u0103ng ho\u1eb7c gi\u1ea3m bao nhi\u00eau l\u1ea7n th\u00ec \u0111\u1ea1i l\u01b0\u1ee3ng c\u00f2n l\u1ea1i s\u1ebd gi\u1ea3m ho\u1eb7c t\u0103ng t\u1eebng \u0111\u00f3 l\u1ea7n.<\/p>\n<p dir=\"ltr\"><em>V\u00ed d\u1ee5: Mu\u1ed1n \u0111\u1eafp xong n\u1ec1n nh\u00e0 trong hai ng\u00e0y, c\u1ea7n c\u00f3 12 ng\u01b0\u1eddi. H\u1ecfi mu\u1ed1n \u0111\u1eafp xong n\u1ec1n nh\u00e0 \u0111\u00f3 trong 4 ng\u00e0y th\u00ec c\u1ea7n c\u00f3 bao nhi\u00eau ng\u01b0\u1eddi? (M\u1ee9c l\u00e0m c\u1ee7a m\u1ed7i ng\u01b0\u1eddi nh\u01b0 nhau)<\/em><\/p>\n<p dir=\"ltr\"><em>T\u00f3m t\u1eaft:<\/em><\/p>\n<p dir=\"ltr\"><em>2 ng\u00e0y: 12 ng\u01b0\u1eddi<\/em><\/p>\n<p dir=\"ltr\"><em>4 ng\u00e0y: \u2026. ng\u01b0\u1eddi?<\/em><\/p>\n<p dir=\"ltr\"><em>B\u00e0i gi\u1ea3i<\/em><\/p>\n<p dir=\"ltr\"><em>C\u00e1ch 1:<\/em><\/p>\n<p dir=\"ltr\"><em>Mu\u1ed1n \u0111\u1eafp xong n\u1ec1n nh\u00e0 trong 1 ng\u00e0y, c\u1ea7n s\u1ed1 ng\u01b0\u1eddi l\u00e0:<\/em><\/p>\n<p dir=\"ltr\"><em>12 \u00d7 2 = 24 (ng\u01b0\u1eddi) (*)<\/em><\/p>\n<p dir=\"ltr\"><em>Mu\u1ed1n \u0111\u1eafp xong n\u1ec1n nh\u00e0 trong 4 ng\u00e0y, c\u1ea7n s\u1ed1 ng\u01b0\u1eddi l\u00e0:<\/em><\/p>\n<p dir=\"ltr\"><em>24 : 4 = 6 (ng\u01b0\u1eddi)<\/em><\/p>\n<p dir=\"ltr\"><em>\u0110\u00e1p s\u1ed1: 6 ng\u01b0\u1eddi<\/em><\/p>\n<p dir=\"ltr\"><em>C\u00e1ch 2:<\/em><\/p>\n<p dir=\"ltr\"><em>4 ng\u00e0y g\u1ea5p 2 ng\u00e0y s\u1ed1 l\u1ea7n l\u00e0:<\/em><\/p>\n<p dir=\"ltr\"><em>4 : 2 = 2 (l\u1ea7n)<\/em><\/p>\n<p dir=\"ltr\"><em>Mu\u1ed1n \u0111\u1eafp xong n\u1ec1n nh\u00e0 trong 4 ng\u00e0y, c\u1ea7n s\u1ed1 ng\u01b0\u1eddi l\u00e0:<\/em><\/p>\n<p dir=\"ltr\"><em>12 : 2 = 6 (ng\u01b0\u1eddi)<\/em><\/p>\n<p dir=\"ltr\"><em>\u0110\u00e1p s\u1ed1: 6 ng\u01b0\u1eddi<\/em><\/p>\n<h3 dir=\"ltr\"><span class=\"ez-toc-section\" id=\"Ti_so_phan_tram\"><\/span>T\u1ec9 s\u1ed1 ph\u1ea7n tr\u0103m<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p dir=\"ltr\">T\u1ec9 s\u1ed1 ph\u1ea7n tr\u0103m l\u00e0 ph\u1ea7n ki\u1ebfn th\u1ee9c kh\u00f4ng ch\u1ec9 \u1ee9ng d\u1ee5ng trong to\u00e1n h\u1ecdc l\u1edbp 4 m\u00e0 c\u00f2n c\u1ea3 th\u1ef1c ti\u1ec5n. K\u00fd hi\u1ec7u %.<\/p>\n<p dir=\"ltr\">Quy t\u1eafc 1: \u0110\u1ec3 t\u00ecm \u0111\u01b0\u1ee3c t\u1ec9 s\u1ed1 ph\u1ea7n tr\u0103m c\u1ee7a hai s\u1ed1 th\u00ec c\u00e1c em c\u1ea7n ph\u1ea3i l\u00e0m theo c\u00e1c b\u01b0\u1edbc nh\u01b0 sau:<\/p>\n<ul>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">B\u01b0\u1edbc 1: T\u00ecm th\u01b0\u01a1ng c\u1ee7a hai s\u1ed1 \u0111\u00f3 d\u01b0\u1edbi d\u1ea1ng s\u1ed1 th\u1eadp ph\u00e2n.<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">B\u01b0\u1edbc 2: Nh\u00e2n th\u01b0\u01a1ng \u0111\u00f3 v\u1edbi 100 v\u00e0 vi\u1ebft th\u00eam k\u00ed hi\u1ec7u ph\u1ea7n tr\u0103m (%) v\u00e0o b\u00ean ph\u1ea3i t\u00edch t\u00ecm \u0111\u01b0\u1ee3c.<\/p>\n<\/li>\n<\/ul>\n<p dir=\"ltr\">C\u00f4ng th\u1ee9c: a : b = T (STP) = STP \u00d7 100 (%)<\/p>\n<p dir=\"ltr\"><em>V\u00ed d\u1ee5: T\u00ecm t\u1ec9 s\u1ed1 ph\u1ea7n tr\u0103m c\u1ee7a 315 v\u00e0 600<\/em><\/p>\n<p dir=\"ltr\"><em>Gi\u1ea3i<\/em><\/p>\n<p dir=\"ltr\"><em>T\u1ec9 s\u1ed1 ph\u1ea7n tr\u0103m c\u1ee7a 315 v\u00e0 600 l\u00e0:<\/em><\/p>\n<p dir=\"ltr\"><em>315 : 600 = 0,525 = 52,5 %<\/em><\/p>\n<p dir=\"ltr\"><em>\u0110\u00e1p s\u1ed1: 52,5 %<\/em><\/p>\n<p dir=\"ltr\">Quy t\u1eafc 2: \u0110\u1ec3 t\u00ecm gi\u00e1 tr\u1ecb % c\u1ee7a s\u1ed1 cho tr\u01b0\u1edbc, ta ch\u1ec9 c\u1ea7n l\u1ea5y gi\u00e1 tr\u1ecb \u0111\u00f3 chia cho 100 r\u1ed3i nh\u00e2n s\u1ed1 % ho\u1eb7c l\u1ea5y s\u1ed1 \u0111\u00f3 nh\u00e2n v\u1edbi s\u1ed1 % r\u1ed3i chia cho 100.<\/p>\n<p dir=\"ltr\">C\u00f4ng th\u1ee9c: Gi\u00e1 tr\u1ecb % = S\u1ed1 A : 100 \u00d7 s\u1ed1 % ho\u1eb7c Gi\u00e1 tr\u1ecb % = S\u1ed1 A \u00d7 s\u1ed1 % : 100<\/p>\n<p dir=\"ltr\"><em>V\u00ed d\u1ee5: Tr\u01b0\u1eddng \u0110\u1ea1i T\u1eeb c\u00f3 600 h\u1ecdc sinh. S\u1ed1 h\u1ecdc sinh n\u1eef chi\u1ebfm 45% s\u1ed1 h\u1ecdc sinh to\u00e0n tr\u01b0\u1eddng. T\u00ednh s\u1ed1 h\u1ecdc sinh n\u1eef c\u1ee7a tr\u01b0\u1eddng.<\/em><\/p>\n<p dir=\"ltr\"><em>Gi\u1ea3i<\/em><\/p>\n<p dir=\"ltr\"><em>S\u1ed1 h\u1ecdc sinh c\u1ee7a tr\u01b0\u1eddng \u0111\u00f3 l\u00e0:<\/em><\/p>\n<p dir=\"ltr\"><em>600 : 100 \u00d7 45 = 270 (h\u1ecdc sinh)<\/em><\/p>\n<p dir=\"ltr\">\u0110\u00e1p s\u1ed1: 270 h\u1ecdc sinh<\/p>\n<p dir=\"ltr\">Quy t\u1eafc 3: \u0110\u1ec3 t\u00ecm m\u1ed9t s\u1ed1 th\u00f4ng qua gi\u00e1 tr\u1ecb ph\u1ea7n tr\u0103m c\u1ee7a ch\u00fang, ta ch\u1ec9 c\u1ea7n l\u1ea5y gi\u00e1 tr\u1ecb \u0111\u00f3 chia cho s\u1ed1 ph\u1ea7n tr\u0103m nh\u00e2n v\u1edbi 100, ho\u1eb7c l\u1ea5y gi\u00e1 tr\u1ecb % nh\u00e2n 100 r\u1ed3i chia cho s\u1ed1 %.<\/p>\n<p dir=\"ltr\">C\u00f4ng th\u1ee9c: S\u1ed1 A = Gi\u00e1 tr\u1ecb % : s\u1ed1 ph\u1ea7n tr\u0103m \u00d7 100 ho\u1eb7c S\u1ed1 A = Gi\u00e1 tr\u1ecb % \u00d7 100 : s\u1ed1 ph\u1ea7n tr\u0103m<\/p>\n<p dir=\"ltr\"><em>V\u00ed d\u1ee5: T\u00ecm m\u1ed9t s\u1ed1 bi\u1ebft 30% c\u1ee7a n\u00f3 b\u1eb1ng 72.<\/em><\/p>\n<p dir=\"ltr\"><em>Gi\u1ea3i<\/em><\/p>\n<p dir=\"ltr\"><em>Gi\u00e1 tr\u1ecb c\u1ee7a s\u1ed1 \u0111\u00f3 l\u00e0:<\/em><\/p>\n<p dir=\"ltr\"><em>72 : 30 \u00d7 100 = 240<\/em><\/p>\n<p dir=\"ltr\"><em>\u0110\u00e1p s\u1ed1: 240<\/em><\/p>\n<p dir=\"ltr\"><img decoding=\"async\" class=\"lazyload\" src=\"https:\/\/external-content.duckduckgo.com\/iu\/?u=https:\/\/vnmedia2.monkeyuni.net\/upload\/web\/img\/cac-quy-tac-hoc-toan-lop-4-4.jpg\" alt=\"D\u1ef1a v\u00e0o ki\u1ebfn th\u1ee9c t\u1ec9 s\u1ed1 ph\u1ea7n tr\u0103m gi\u00fap \u1ee9ng d\u1ee5ng nhi\u1ec1u b\u00e0i to\u00e1n trong th\u1ef1c ti\u1ec5n. (\u1ea2nh: S\u01b0u t\u1ea7m internet)\" width=\"100%\"><\/p>\n<h3 dir=\"ltr\"><span class=\"ez-toc-section\" id=\"Cac_quy_tac_toan_hoc_lop_4_ve_dai_luong\"><\/span>C\u00e1c quy t\u1eafc to\u00e1n h\u1ecdc l\u1edbp 4 v\u1ec1 \u0111\u1ea1i l\u01b0\u1ee3ng<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p dir=\"ltr\">C\u00e1c \u0111\u1ea1i l\u01b0\u1ee3ng trong to\u00e1n h\u1ecdc kh\u00e1 nhi\u1ec1u, nh\u01b0ng t\u00ednh \u1ee9ng d\u1ee5ng trong th\u1ef1c ti\u1ec5n r\u1ea5t cao. N\u00ean \u0111\u00f2i h\u1ecfi c\u00e1c em ph\u1ea3i n\u1eafm v\u1eefng \u0111\u1ec3 gi\u1ea3i b\u00e0i t\u1eadp hay \u1ee9ng d\u1ee5ng t\u1ed1t nh\u1ea5t. C\u1ee5 th\u1ec3:<\/p>\n<h4 dir=\"ltr\"><span class=\"ez-toc-section\" id=\"_Bang_don_vi_do_do_dai\"><\/span>* B\u1ea3ng \u0111\u01a1n v\u1ecb \u0111o \u0111\u1ed9 d\u00e0i<span class=\"ez-toc-section-end\"><\/span><\/h4>\n<p dir=\"ltr\"><img decoding=\"async\" class=\"lazyload\" src=\"https:\/\/external-content.duckduckgo.com\/iu\/?u=https:\/\/vnmedia2.monkeyuni.net\/upload\/web\/img\/cac-quy-tac-hoc-toan-lop-4-5.jpg\" alt=\"\" width=\"100%\"><\/p>\n<p dir=\"ltr\">Theo \u0111\u00f3:<\/p>\n<ul>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">M\u1ed7i \u0111\u01a1n v\u1ecb \u0111o \u0111\u1ed9 d\u00e0i \u0111\u1ec1u g\u1ea5p 10 l\u1ea7n \u0111\u01a1n v\u1ecb b\u00e9 h\u01a1n li\u1ec1n sau n\u00f3.<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">M\u1ed7i \u0111\u01a1n v\u1ecb \u0111o \u0111\u1ed9 d\u00e0i \u0111\u1ec1u k\u00e9m h\u01a1n 10 l\u1ea7n \u0111\u01a1n v\u1ecb l\u1edbn h\u01a1n li\u1ec1n tr\u01b0\u1edbc n\u00f3.<\/p>\n<\/li>\n<\/ul>\n<h4 dir=\"ltr\"><span class=\"ez-toc-section\" id=\"_Bang_don_vi_do_khoi_luong\"><\/span>* B\u1ea3ng \u0111\u01a1n v\u1ecb \u0111o kh\u1ed1i l\u01b0\u1ee3ng<span class=\"ez-toc-section-end\"><\/span><\/h4>\n<p dir=\"ltr\">D\u01b0\u1edbi \u0111\u00e2y l\u00e0 b\u1ea3ng \u0111\u01a1n v\u1ecb \u0111o kh\u1ed1i l\u01b0\u1ee3ng chi ti\u1ebft nh\u1ea5t:<\/p>\n<p dir=\"ltr\"><img decoding=\"async\" class=\"lazyload\" src=\"https:\/\/external-content.duckduckgo.com\/iu\/?u=https:\/\/vnmedia2.monkeyuni.net\/upload\/web\/img\/cac-quy-tac-hoc-toan-lop-4-6.jpg\" alt=\"\" width=\"100%\"><\/p>\n<ul>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">\u0110\u1ec3 \u0111o c\u00e1c \u0111\u1ed3 v\u1eadt h\u00e0ng h\u00e0ng ch\u1ee5c, tr\u0103m, ng\u00e0n ki l\u00f4 gam ta s\u1ebd d\u00f9ng \u0111\u01a1n v\u1ecb y\u1ebfn t\u1ea1 t\u1ea5n.<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">\u0110\u1ec3 \u0111o c\u00e1c \u0111\u1ed3 v\u1eadt n\u1eb7ng t\u1eeb h\u00e0ng ch\u1ee5c, tr\u0103m, ng\u00e0n gam ta d\u00f9ng \u0111\u1ec1-ca-gam, h\u00e9c-t\u00f4-gam.<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">M\u1ed7i \u0111\u01a1n v\u1ecb \u0111o kh\u1ed1i l\u01b0\u1ee3ng \u0111\u1ec1u g\u1ea5p 10 l\u1ea7n \u0111\u01a1n v\u1ecb b\u00e9 h\u01a1n li\u1ec1n sau n\u00f3.<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">M\u1ed7i \u0111\u01a1n v\u1ecb \u0111o kh\u1ed1i l\u01b0\u1ee3ng \u0111\u1ec1u k\u00e9m h\u01a1n 10 l\u1ea7n \u0111\u01a1n l\u1edbn h\u01a1n li\u1ec1n tr\u01b0\u1edbc n\u00f3.<\/p>\n<\/li>\n<\/ul>\n<h4 dir=\"ltr\"><span class=\"ez-toc-section\" id=\"_Bang_don_vi_do_dien_tich\"><\/span>* B\u1ea3ng \u0111\u01a1n v\u1ecb \u0111o di\u1ec7n t\u00edch<span class=\"ez-toc-section-end\"><\/span><\/h4>\n<p dir=\"ltr\"><img decoding=\"async\" class=\"lazyload\" src=\"https:\/\/external-content.duckduckgo.com\/iu\/?u=https:\/\/vnmedia2.monkeyuni.net\/upload\/web\/img\/cac-quy-tac-hoc-toan-lop-4-7a.jpg\" alt=\"\" width=\"100%\"><\/p>\n<p dir=\"ltr\">L\u01b0u \u00fd: Trong b\u1ea3ng \u0111\u01a1n v\u1ecb \u0111o di\u1ec7n t\u00edch, hai \u0111\u01a1n v\u1ecb \u0111o di\u1ec7n t\u00edch li\u1ec1n nhau g\u1ea5p (ho\u1eb7c k\u00e9m) nhau 100 l\u1ea7n.<\/p>\n<h4 dir=\"ltr\"><span class=\"ez-toc-section\" id=\"_Bang_don_vi_do_the_tich\"><\/span>* B\u1ea3ng \u0111\u01a1n v\u1ecb \u0111o th\u1ec3 t\u00edch<span class=\"ez-toc-section-end\"><\/span><\/h4>\n<p dir=\"ltr\"><img decoding=\"async\" class=\"lazyload\" src=\"https:\/\/external-content.duckduckgo.com\/iu\/?u=https:\/\/vnmedia2.monkeyuni.net\/upload\/web\/img\/cac-quy-tac-hoc-toan-lop-4-7.jpg\" alt=\"\" width=\"100%\"><\/p>\n<p dir=\"ltr\">Trong \u0111\u00f3: Trong b\u1ea3ng \u0111\u01a1n v\u1ecb \u0111o th\u1ec3 t\u00edch, hai \u0111\u01a1n v\u1ecb \u0111o th\u1ec3 t\u00edch li\u1ec1n nhau g\u1ea5p (ho\u1eb7c k\u00e9m) nhau 1000 l\u1ea7n.<\/p>\n<p dir=\"ltr\">L\u01b0u \u00fd: 1dm3 = 1 l<\/p>\n<h4 dir=\"ltr\"><span class=\"ez-toc-section\" id=\"_Cac_quy_tac_toan_hoc_lop_4_ve_Giay_%E2%80%93_the_ky\"><\/span>* C\u00e1c quy t\u1eafc to\u00e1n h\u1ecdc l\u1edbp 4 v\u1ec1 Gi\u00e2y \u2013 th\u1ebf k\u1ef7<span class=\"ez-toc-section-end\"><\/span><\/h4>\n<p dir=\"ltr\">Gi\u00e2y \u2013 th\u1ebf k\u1ef7 to\u00e1n l\u1edbp 4 l\u00e0 \u0111\u01a1n v\u1ecb \u0111o th\u1eddi gian, gi\u00fap c\u00e1c em luy\u1ec7n t\u1eadp k\u1ef9 n\u0103ng xem gi\u1edd gi\u1ea5c, t\u00ednh to\u00e1n th\u1eddi gian m\u1ed9t c\u00e1ch ch\u00ednh x\u00e1c.<\/p>\n<p dir=\"ltr\">Trong \u0111\u00f3:<\/p>\n<ul>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">1 th\u1ebf k\u1ef7 = 100 n\u0103m<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">T\u1eeb n\u0103m 1 \u0111\u1ebfn n\u0103m 100 l\u00e0 th\u1ebf k\u1ef7 1 (th\u1ebf k\u1ef7 I).<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">T\u1eeb n\u0103m 101 \u0111\u1ebfn n\u0103m 200 l\u00e0 th\u1ebf k\u1ef7 2 (th\u1ebf k\u1ef7 II).<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">T\u1eeb n\u0103m 201 \u0111\u1ebfn n\u0103m 300 l\u00e0 th\u1ebf k\u1ef7 3 (th\u1ebf k\u1ef7 III).<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">1 n\u0103m = 365 ng\u00e0y<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">1 n\u0103m nhu\u1eadn = 366 ng\u00e0y<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">M\u1ed9t n\u0103m c\u00f3 12 th\u00e1ng.<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">Th\u00e1ng 1, 3, 5, 7, 8, 10, 12: c\u00f3 31 ng\u00e0y.<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">Th\u00e1ng 4, 6, 9, 11: c\u00f3 30 ng\u00e0y.<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">Th\u00e1ng hai c\u00f3 28 ng\u00e0y (n\u0103m nhu\u1eadn c\u00f3 29 ng\u00e0y)<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">1 ph\u00fat = 60 gi\u00e2y<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">1 gi\u1edd = 60 ph\u00fat = 3600 gi\u00e2y<\/p>\n<\/li>\n<\/ul>\n<h3 dir=\"ltr\"><span class=\"ez-toc-section\" id=\"On_tap_hinh_hoc\"><\/span>\u00d4n t\u1eadp h\u00ecnh h\u1ecdc<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p dir=\"ltr\">B\u00ean c\u1ea1nh \u0111\u1ea1i s\u1ed1, h\u00ecnh h\u1ecdc to\u00e1n l\u1edbp 4 c\u0169ng s\u1ebd bao g\u1ed3m nhi\u1ec1u ki\u1ebfn th\u1ee9c, quy t\u1eafc quan tr\u1ecdng m\u00e0 c\u00e1c em c\u1ea7n ph\u1ea3i n\u1eafm r\u00f5 \u0111\u1ec3 chinh ph\u1ee5c b\u00e0i t\u1eadp v\u00e0 \u1ee9ng d\u1ee5ng trong th\u1ef1c ti\u1ec5n. C\u1ee5 th\u1ec3:<\/p>\n<h4 dir=\"ltr\"><span class=\"ez-toc-section\" id=\"_Hinh_vuong\"><\/span>* H\u00ecnh vu\u00f4ng<span class=\"ez-toc-section-end\"><\/span><\/h4>\n<p dir=\"ltr\">H\u00ecnh vu\u00f4ng l\u00e0 t\u1ee9 gi\u00e1c c\u00f3 4 g\u00f3c vu\u00f4ng, 4 c\u1ea1nh d\u00e0i b\u1eb1ng nhau.<\/p>\n<p dir=\"ltr\">C\u00f4ng th\u1ee9c t\u00ednh chu vi h\u00ecnh vu\u00f4ng: Mu\u1ed1n t\u00ednh chu vi h\u00ecnh vu\u00f4ng, ta l\u1ea5y s\u1ed1 \u0111o m\u1ed9t c\u1ea1nh nh\u00e2n v\u1edbi 4.<\/p>\n<p dir=\"ltr\">\u2192 P = a x 4<\/p>\n<p dir=\"ltr\">Trong \u0111\u00f3: a l\u00e0 c\u1ea1nh v\u00e0 P l\u00e0 chu vi.<\/p>\n<p dir=\"ltr\">Mu\u1ed1n t\u00ecm m\u1ed9t c\u1ea1nh h\u00ecnh vu\u00f4ng, ta l\u1ea5y chu vi chia cho 4.<\/p>\n<p dir=\"ltr\">\u2192 a = P : 4<\/p>\n<p dir=\"ltr\">C\u00f4ng th\u1ee9c t\u00ednh di\u1ec7n t\u00edch h\u00ecnh vu\u00f4ng: Ta l\u1ea5y s\u1ed1 \u0111o m\u1ed9t c\u1ea1nh nh\u00e2n v\u1edbi ch\u00ednh n\u00f3.<\/p>\n<p dir=\"ltr\">\u2192 S = a x a<\/p>\n<p dir=\"ltr\">\u0110\u1ec3 t\u00ecm 1 c\u1ea1nh h\u00ecnh vu\u00f4ng khi bi\u1ebft di\u1ec7n t\u00edch, ta t\u00ecm xem m\u1ed9t s\u1ed1 n\u00e0o \u0111\u00f3 nh\u00e2n v\u1edbi ch\u00ednh n\u00f3 b\u1eb1ng di\u1ec7n t\u00edch, th\u00ec \u0111\u00f3 l\u00e0 c\u1ea1nh.<\/p>\n<p dir=\"ltr\"><img decoding=\"async\" class=\"lazyload\" src=\"https:\/\/external-content.duckduckgo.com\/iu\/?u=https:\/\/vnmedia2.monkeyuni.net\/upload\/web\/img\/cac-quy-tac-hoc-toan-lop-4-8.jpg\" alt=\"H\u00ecnh vu\u00f4ng l\u00e0 h\u00ecnh h\u1ecdc c\u01a1 b\u1ea3n c\u00e1c em s\u1ebd h\u1ecdc trong ch\u01b0\u01a1ng tr\u00ecnh to\u00e1n l\u1edbp 4. (\u1ea2nh: S\u01b0u t\u1ea7m internet)\" width=\"100%\"><\/p>\n<h4 dir=\"ltr\"><span class=\"ez-toc-section\" id=\"_Hinh_chu_nhat\"><\/span>* H\u00ecnh ch\u1eef nh\u1eadt<span class=\"ez-toc-section-end\"><\/span><\/h4>\n<p dir=\"ltr\">H\u00ecnh ch\u1eef nh\u1eadt l\u00e0 t\u1ee9 gi\u00e1c c\u00f3 4 g\u00f3c vu\u00f4ng, 2 chi\u1ec1u d\u00e0i b\u1eb1ng nhau, 2 chi\u1ec1u r\u1ed9ng b\u1eb1ng nhau.<\/p>\n<p dir=\"ltr\">C\u00f4ng th\u1ee9c t\u00ednh chu vi: Ta l\u1ea5y s\u1ed1 \u0111o chi\u1ec1u d\u00e0i c\u1ed9ng s\u1ed1 \u0111o chi\u1ec1u r\u1ed9ng(c\u00f9ng \u0111\u01a1n v\u1ecb \u0111o) r\u1ed3i nh\u00e2n v\u1edbi 2.<\/p>\n<p dir=\"ltr\">\u2192 P = (a + b) \u00d7 2<\/p>\n<p dir=\"ltr\">Trong \u0111\u00f3: chi\u1ec1u d\u00e0i l\u00e0 a, chi\u1ec1u r\u1ed9ng l\u00e0 b v\u00e0 P l\u00e0 chu vi.<\/p>\n<p dir=\"ltr\">\u0110\u1ec3 t\u00ecm chi\u1ec1u d\u00e0i, ta l\u1ea5y chu vi chia cho 2 r\u1ed3i tr\u1eeb \u0111i chi\u1ec1u r\u1ed9ng. a = P : 2 &#8211; b<\/p>\n<p dir=\"ltr\">\u0110\u1ec3 t\u00ecm chi\u1ec1u r\u1ed9ng, ta l\u1ea5y chu vi chia cho 2 r\u1ed3i tr\u1eeb \u0111i chi\u1ec1u d\u00e0i. b = P : 2 &#8211; a<\/p>\n<p dir=\"ltr\">C\u00f4ng th\u1ee9c t\u00ednh di\u1ec7n t\u00edch: ta l\u1ea5y s\u1ed1 \u0111o chi\u1ec1u d\u00e0i nh\u00e2n v\u1edbi s\u1ed1 \u0111o chi\u1ec1u r\u1ed9ng (c\u00f9ng \u0111\u01a1n v\u1ecb \u0111o).<\/p>\n<p dir=\"ltr\">\u2192 S = a \u00d7 b<\/p>\n<p dir=\"ltr\">\u0110\u1ec3 t\u00ecm chi\u1ec1u d\u00e0i, ta l\u1ea5y di\u1ec7n t\u00edch chia cho chi\u1ec1u r\u1ed9ng. a = S : b<\/p>\n<p dir=\"ltr\">\u0110\u1ec3 t\u00ecm chi\u1ec1u r\u1ed9ng, ta l\u1ea5y di\u1ec7n t\u00edch chia cho chi\u1ec1u d\u00e0i. b = S : a<\/p>\n<p dir=\"ltr\"><img decoding=\"async\" class=\"lazyload\" src=\"https:\/\/external-content.duckduckgo.com\/iu\/?u=https:\/\/vnmedia2.monkeyuni.net\/upload\/web\/img\/cac-quy-tac-hoc-toan-lop-4-9.jpg\" alt=\"H\u1ecdc sinh c\u1ea7n n\u1eafm v\u1eefng c\u00e1c quy t\u1eafc, c\u00f4ng th\u1ee9c h\u00ecnh ch\u1eef nh\u1eadt to\u00e1n l\u1edbp 4. (\u1ea2nh: S\u01b0u t\u1ea7m internet)\" width=\"100%\"><\/p>\n<h4 dir=\"ltr\"><span class=\"ez-toc-section\" id=\"_Hinh_binh_hanh\"><\/span>* H\u00ecnh b\u00ecnh h\u00e0nh<span class=\"ez-toc-section-end\"><\/span><\/h4>\n<p dir=\"ltr\">H\u00ecnh b\u00ecnh h\u00e0nh c\u00f3 hai c\u1eb7p c\u1ea1nh \u0111\u1ed1i di\u1ec7n song song v\u00e0 b\u1eb1ng nhau.<\/p>\n<p dir=\"ltr\">C\u00f4ng th\u1ee9c t\u00ednh chu vi h\u00ecnh b\u00ecnh h\u00e0nh: Ta t\u00ednh b\u1eb1ng t\u1ed5ng \u0111\u1ed9 d\u00e0i c\u1ee7a 4 c\u1ea1nh ho\u1eb7c b\u1eb1ng t\u1ed5ng hai c\u1ea1nh \u0111\u00e1y nh\u00e2n v\u1edbi 2.<\/p>\n<p dir=\"ltr\">\u2192 P = (a + b) x 2<\/p>\n<p dir=\"ltr\">C\u00f4ng th\u1ee9c t\u00ednh di\u1ec7n t\u00edch h\u00ecnh b\u00ecnh h\u00e0nh: ta l\u1ea5y \u0111\u1ed9 d\u00e0i \u0111\u00e1y nh\u00e2n v\u1edbi chi\u1ec1u cao (c\u00f9ng \u0111\u01a1n v\u1ecb \u0111o)<\/p>\n<p dir=\"ltr\">\u2192 S = a \u00d7 h<\/p>\n<p dir=\"ltr\">\u0110\u1ec3 t\u00ecm \u0111\u1ed9 d\u00e0i \u0111\u00e1y, ta l\u1ea5y di\u1ec7n t\u00edch chia cho chi\u1ec1u cao. a = S : b<\/p>\n<p dir=\"ltr\">\u0110\u1ec3 t\u00ecm chi\u1ec1u r\u1ed9ng, ta l\u1ea5y di\u1ec7n t\u00edch chia cho chi\u1ec1u d\u00e0i. b = S : a<\/p>\n<p dir=\"ltr\">Trong \u0111\u00f3: \u0110\u00e1y l\u00e0 a, chi\u1ec1u cao l\u00e0 h<\/p>\n<p dir=\"ltr\"><img decoding=\"async\" class=\"lazyload\" src=\"https:\/\/external-content.duckduckgo.com\/iu\/?u=https:\/\/vnmedia2.monkeyuni.net\/upload\/web\/img\/cac-quy-tac-hoc-toan-lop-4-10.jpg\" alt=\"M\u1ed9t s\u1ed1 c\u00f4ng th\u1ee9c v\u1ec1 h\u00ecnh b\u00ecnh h\u00e0nh. (\u1ea2nh: S\u01b0u t\u1ea7m internet)\" width=\"100%\"><\/p>\n<h4 dir=\"ltr\"><span class=\"ez-toc-section\" id=\"_Hinh_thoi\"><\/span>* H\u00ecnh thoi<span class=\"ez-toc-section-end\"><\/span><\/h4>\n<p dir=\"ltr\">T\u00ednh ch\u1ea5t:<\/p>\n<ul>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">H\u00ecnh thoi c\u00f3 hai c\u1eb7p c\u1ea1nh \u0111\u1ed1i di\u1ec7n song song v\u00e0 b\u1ed1n c\u1ea1nh b\u1eb1ng nhau<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">H\u00ecnh thoi c\u00f3 hai \u0111\u01b0\u1eddng ch\u00e9o vu\u00f4ng g\u00f3c v\u1edbi nhau v\u00e0 c\u1eaft nhau t\u1ea1i trung \u0111i\u1ec3m c\u1ee7a m\u1ed7i \u0111\u01b0\u1eddng.<\/p>\n<\/li>\n<\/ul>\n<p dir=\"ltr\">C\u00f4ng th\u1ee9c t\u00ednh chu vi h\u00ecnh thoi: Ta l\u1ea5y s\u1ed1 \u0111o m\u1ed9t c\u1ea1nh nh\u00e2n v\u1edbi 4.<\/p>\n<p dir=\"ltr\">\u2192 P = a x 4<\/p>\n<p dir=\"ltr\">C\u00f4ng th\u1ee9c t\u00ednh di\u1ec7n t\u00edch h\u00ecnh thoi: Ta l\u1ea5y t\u00edch c\u1ee7a \u0111\u1ed9 d\u00e0i hai \u0111\u01b0\u1eddng ch\u00e9o chia cho 2 (c\u00f9ng \u0111\u01a1n v\u1ecb \u0111o).\u00a0<\/p>\n<p dir=\"ltr\">\u2192 S = \u00bd x (m x n ) ho\u1eb7c S = h x a<\/p>\n<p dir=\"ltr\">Trong \u0111\u00f3:<\/p>\n<ul>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">a: C\u1ea1nh h\u00ecnh thoi<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">h: Chi\u1ec1u cao h\u00ecnh thoi<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">m, n: Hai \u0111\u01b0\u1eddng ch\u00e9o<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">P: Chu vi<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">S: Di\u1ec7n t\u00edch<\/p>\n<\/li>\n<\/ul>\n<p dir=\"ltr\"><img decoding=\"async\" class=\"lazyload\" src=\"https:\/\/external-content.duckduckgo.com\/iu\/?u=https:\/\/vnmedia2.monkeyuni.net\/upload\/web\/img\/cac-quy-tac-hoc-toan-lop-4-11.jpg\" alt=\"H\u00ecnh thoi - H\u00ecnh h\u1ecdc c\u01a1 b\u1ea3n trong to\u00e1n h\u1ecdc c\u1ea7n n\u1eafm v\u1eefng c\u00e1c c\u00f4ng th\u1ee9c.(\u1ea2nh: S\u01b0u t\u1ea7m internet)\" width=\"100%\"><\/p>\n<h4 dir=\"ltr\"><span class=\"ez-toc-section\" id=\"_Hinh_thang\"><\/span>* H\u00ecnh thang<span class=\"ez-toc-section-end\"><\/span><\/h4>\n<p dir=\"ltr\">H\u00ecnh thang c\u00f3 m\u1ed9t c\u1eb7p c\u1ea1nh \u0111\u1ed1i di\u1ec7n song song. Trong \u0111\u00f3 chi\u1ec1u cao ch\u00ednh l\u00e0 \u0111o\u1ea1n th\u1eb3ng \u1edf gi\u1eefa hai \u0111\u00e1y v\u00e0 vu\u00f4ng g\u00f3c v\u1edbi hai \u0111\u00e1y.<\/p>\n<p dir=\"ltr\">C\u00f4ng th\u1ee9c t\u00ednh di\u1ec7n t\u00edch h\u00ecnh thang: Ta l\u1ea5y t\u1ed5ng \u0111\u1ed9 d\u00e0i hai \u0111\u00e1y nh\u00e2n v\u1edbi chi\u1ec1u cao (c\u00f9ng \u0111\u01a1n v\u1ecb \u0111o) r\u1ed3i chia cho 2.<\/p>\n<p dir=\"ltr\">\u2192 S = (a + b) x h : 2<\/p>\n<p dir=\"ltr\">\u0110\u1ec3 t\u00ednh t\u1ed5ng hai \u0111\u00e1y h\u00ecnh thoi ta l\u1ea5y di\u1ec7n t\u00edch nh\u00e2n v\u1edbi 2 r\u1ed3i chia cho chi\u1ec1u cao.<\/p>\n<p dir=\"ltr\">\u2192 (a + b) = S x 2 : h<\/p>\n<p dir=\"ltr\">\u0110\u1ec3 t\u00ednh trung b\u00ecnh c\u1ed9ng hai \u0111\u00e1y ta l\u1ea5y di\u1ec7n t\u00edch chia cho chi\u1ec1u cao.\u00a0<\/p>\n<p dir=\"ltr\">\u2192 a ho\u1eb7c b= S : h<\/p>\n<p dir=\"ltr\">\u0110\u1ec3 t\u00ednh \u0111\u1ed9 d\u00e0i \u0111\u00e1y l\u1edbn h\u00ecnh thang: Ta l\u1ea5y di\u1ec7n t\u00edch nh\u00e2n v\u1edbi 2, chia cho chi\u1ec1u cao r\u1ed3i tr\u1eeb \u0111i \u0111\u1ed9 d\u00e0i \u0111\u00e1y b\u00e9.\u00a0<\/p>\n<p dir=\"ltr\">\u2192 a = S x 2 : h &#8211; b<\/p>\n<p dir=\"ltr\">\u0110\u1ec3 t\u00ednh \u0111\u1ed9 d\u00e0i \u0111\u00e1y b\u00e9 h\u00ecnh thang: Ta l\u1ea5y di\u1ec7n t\u00edch nh\u00e2n v\u1edbi 2, chia cho chi\u1ec1u cao r\u1ed3i tr\u1eeb \u0111i \u0111\u1ed9 d\u00e0i \u0111\u00e1y l\u1edbn.<\/p>\n<p dir=\"ltr\">\u2192 b = S x 2 : h &#8211; a<\/p>\n<p dir=\"ltr\">\u0110\u1ec3 t\u00ednh chi\u1ec1u cao h\u00ecnh thang: Ta l\u1ea5y di\u1ec7n t\u00edch nh\u00e2n v\u1edbi 2 r\u1ed3i chia cho t\u1ed5ng \u0111\u1ed9 d\u00e0i hai \u0111\u00e1y.<\/p>\n<p dir=\"ltr\">\u2192 h = S x 2 : (a + b)<\/p>\n<p dir=\"ltr\">ho\u1eb7c: T\u00ednh chi\u1ec1u cao: Ta l\u1ea5y di\u1ec7n t\u00edch chia cho trung b\u00ecnh c\u1ed9ng c\u1ee7a hai \u0111\u00e1y.<\/p>\n<p dir=\"ltr\">Trong \u0111\u00f3: \u0111\u00e1y l\u1edbn l\u00e0 a, \u0111\u00e1y nh\u1ecf l\u00e0 b, chi\u1ec1u cao l\u00e0 h<\/p>\n<p dir=\"ltr\"><img decoding=\"async\" class=\"lazyload\" src=\"https:\/\/external-content.duckduckgo.com\/iu\/?u=https:\/\/vnmedia2.monkeyuni.net\/upload\/web\/img\/cac-quy-tac-hoc-toan-lop-4-12.jpg\" alt=\"M\u1ed9t s\u1ed1 c\u00f4ng th\u1ee9c h\u00ecnh thang th\u01b0\u1eddng g\u1eb7p. (\u1ea2nh: S\u01b0u t\u1ea7m internet)\" width=\"100%\"><\/p>\n<h4 dir=\"ltr\"><span class=\"ez-toc-section\" id=\"_Hinh_tam_giac\"><\/span>* H\u00ecnh tam gi\u00e1c<span class=\"ez-toc-section-end\"><\/span><\/h4>\n<p dir=\"ltr\">H\u00ecnh tam gi\u00e1c c\u00f3 ba c\u1ea1nh, 3 g\u00f3c, 3 \u0111\u1ec9nh. Chi\u1ec1u cao h\u00ecnh tam gi\u00e1c ch\u00ednh l\u00e0 \u0111o\u1ea1n th\u1eb3ng h\u1ea1 t\u1eeb \u0111\u1ec9nh vu\u00f4ng g\u00f3c v\u1edbi c\u1ea1nh \u0111\u1ed1i di\u1ec7n.<\/p>\n<p dir=\"ltr\">C\u00f4ng th\u1ee9c t\u00ednh chu vi h\u00ecnh tam gi\u00e1c: B\u1eb1ng t\u1ed5ng \u0111\u1ed9 d\u00e0i c\u1ee7a 3 c\u1ea1nh.<\/p>\n<p dir=\"ltr\">\u2192 P = a + b + c<\/p>\n<p dir=\"ltr\">C\u00f4ng th\u1ee9c t\u00ednh di\u1ec7n t\u00edch h\u00ecnh tam gi\u00e1c: Ta l\u1ea5y \u0111\u1ed9 d\u00e0i \u0111\u00e1y nh\u00e2n v\u1edbi chi\u1ec1u cao (c\u00f9ng \u0111\u01a1n v\u1ecb \u0111o) r\u1ed3i chia cho 2.<\/p>\n<p dir=\"ltr\">\u2192 S = a x h : 2<\/p>\n<p dir=\"ltr\">\u0110\u1ec3 t\u00ednh c\u1ea1nh \u0111\u00e1y h\u00ecnh tam gi\u00e1c: Ta l\u1ea5y di\u1ec7n t\u00edch nh\u00e2n v\u1edbi 2 r\u1ed3i chia cho chi\u1ec1u cao.<\/p>\n<p dir=\"ltr\">\u2192 a = S x 2 : h<\/p>\n<p dir=\"ltr\">\u0110\u1ec3 t\u00ednh chi\u1ec1u cao h\u00ecnh tam gi\u00e1c: Ta l\u1ea5y di\u1ec7n t\u00edch nh\u00e2n v\u1edbi 2 r\u1ed3i chia cho c\u1ea1nh \u0111\u00e1y.<\/p>\n<p dir=\"ltr\">\u2192 h = S x 2 : a<\/p>\n<p dir=\"ltr\"><img decoding=\"async\" class=\"lazyload\" src=\"https:\/\/external-content.duckduckgo.com\/iu\/?u=https:\/\/vnmedia2.monkeyuni.net\/upload\/web\/img\/cac-quy-tac-hoc-toan-lop-4-13.jpg\" alt=\"Trong h\u00ecnh h\u1ecdc, h\u00ecnh tam gi\u00e1c c\u00f3 nhi\u1ec1u th\u1ec3 lo\u1ea1i h\u00ecnh kh\u00e1c nhau. (\u1ea2nh: S\u01b0u t\u1ea7m internet)\" width=\"100%\"><\/p>\n<h4 dir=\"ltr\"><span class=\"ez-toc-section\" id=\"_Hinh_tron\"><\/span>* H\u00ecnh tr\u00f2n<span class=\"ez-toc-section-end\"><\/span><\/h4>\n<ul>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">H\u00ecnh tr\u00f2n c\u00f3 t\u1ea5t c\u1ea3 c\u00e1c b\u00e1n k\u00ednh b\u1eb1ng nhau.<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">\u0110\u01b0\u1eddng bao quanh h\u00ecnh tr\u00f2n g\u1ecdi l\u00e0 \u0111\u01b0\u1eddng tr\u00f2n.<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">\u0110i\u1ec3m ch\u00ednh gi\u1eefa h\u00ecnh tr\u00f2n l\u00e0 t\u00e2m.<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">\u0110o\u1ea1n th\u1eb3ng n\u1ed1i t\u00e2m v\u1edbi m\u1ed9t \u0111i\u1ec3m tr\u00ean \u0111\u01b0\u1eddng tr\u00f2n g\u1ecdi l\u00e0 b\u00e1n k\u00ednh. Ki hi\u1ec7u l\u00e0 r<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">\u0110o\u1ea1n th\u1eb3ng \u0111i qua t\u00e2m v\u00e0 n\u1ed1i hai \u0111i\u1ec3m c\u1ee7a \u0111\u01b0\u1eddng tr\u00f2n g\u1ecdi l\u00e0 \u0111\u01b0\u1eddng k\u00ednh.<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">\u0110\u01b0\u1eddng k\u00ednh g\u1ea5p hai l\u1ea7n b\u00e1n k\u00ednh. K\u00ed hi\u1ec7u l\u00e0 d<\/p>\n<\/li>\n<\/ul>\n<p dir=\"ltr\">C\u00f4ng th\u1ee9c t\u00ednh chu vi h\u00ecnh tr\u00f2n: Ta l\u1ea5y \u0111\u01b0\u1eddng k\u00ednh nh\u00e2n v\u1edbi s\u1ed1 3,14.<\/p>\n<p dir=\"ltr\">\u2192 C = d x 3,14<\/p>\n<p dir=\"ltr\">Ho\u1eb7c ta l\u1ea5y b\u00e1n k\u00ednh nh\u00e2n 2 r\u1ed3i nh\u00e2n v\u1edbi s\u1ed1 3,14.<\/p>\n<p dir=\"ltr\">\u2192 C = r x 2 x 3,14<\/p>\n<p dir=\"ltr\">\u0110\u1ec3 t\u00ednh \u0111\u01b0\u1eddng k\u00ednh h\u00ecnh tr\u00f2n: Ta l\u1ea5y chu vi chia cho s\u1ed1 3,14<\/p>\n<p dir=\"ltr\">\u2192 d = C : 3,14<\/p>\n<p dir=\"ltr\">\u0110\u1ec3 t\u00ednh b\u00e1n k\u00ednh h\u00ecnh tr\u00f2n: ta l\u1ea5y chu vi chia cho 2 r\u1ed3i chia cho s\u1ed1 3,14<\/p>\n<p dir=\"ltr\">\u2192 r = C : 2 : 3,14 (T\u00ednh ra nh\u00e1p: r = C : 6,28)<\/p>\n<p dir=\"ltr\">C\u00f4ng th\u1ee9c t\u00ednh di\u1ec7n t\u00edch h\u00ecnh tr\u00f2n: Ta l\u1ea5y b\u00e1n k\u00ednh nh\u00e2n v\u1edbi b\u00e1n k\u00ednh r\u1ed3i nh\u00e2n v\u1edbi s\u1ed1 3,14.\u00a0<\/p>\n<p dir=\"ltr\">\u2192 S = r x r x 3,14<\/p>\n<p dir=\"ltr\"><img decoding=\"async\" class=\"lazyload\" src=\"https:\/\/external-content.duckduckgo.com\/iu\/?u=https:\/\/vnmedia2.monkeyuni.net\/upload\/web\/img\/cac-quy-tac-hoc-toan-lop-4-14.jpg\" alt=\"H\u00ecnh tr\u00f2n l\u00e0 h\u00ecnh h\u1ecdc \u0111\u1eb7c bi\u1ec7t trong to\u00e1n h\u1ecdc. (\u1ea2nh: S\u01b0u t\u1ea7m internet)\" width=\"100%\"><\/p>\n<h4 dir=\"ltr\"><span class=\"ez-toc-section\" id=\"_Hinh_hop_chu_nhat\"><\/span>* H\u00ecnh h\u1ed9p ch\u1eef nh\u1eadt<span class=\"ez-toc-section-end\"><\/span><\/h4>\n<ul>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">H\u00ecnh h\u1ed9p ch\u1eef nh\u1eadt c\u00f3 6 m\u1eb7t, hai m\u1eb7t \u0111\u00e1y v\u00e0 b\u1ed1n m\u1eb7t b\u00ean.<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">C\u00f3 8 \u0111\u1ec9nh, 12 c\u1ea1nh<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">C\u00f3 ba k\u00edch th\u01b0\u1edbc: chi\u1ec1u d\u00e0i (a), chi\u1ec1u r\u1ed9ng (b), chi\u1ec1u cao (c).<\/p>\n<\/li>\n<\/ul>\n<p dir=\"ltr\">C\u00f4ng th\u1ee9c t\u00ednh di\u1ec7n t\u00edch xung quanh h\u00ecnh h\u1ed9p ch\u1eef nh\u1eadt: Ta l\u1ea5y chu vi \u0111\u00e1y nh\u00e2n v\u1edbi chi\u1ec1u cao (c\u00f9ng m\u1ed9t \u0111\u01a1n v\u1ecb \u0111o).<\/p>\n<p dir=\"ltr\">\u2192 S(xung quanh) = P(\u0111\u00e1y) x c Ho\u1eb7c: S(xung quanh) = (a + b) x 2 x c<\/p>\n<p dir=\"ltr\">\u0110\u1ec3 t\u00ecm chu vi \u0111\u00e1y, ta l\u1ea5y di\u1ec7n t\u00edch xung quanh chia cho chi\u1ec1u cao.<\/p>\n<p dir=\"ltr\">\u2192 P (\u0111\u00e1y) = S(xung quanh) : c<\/p>\n<p dir=\"ltr\">\u0110\u1ec3 t\u00ecm chi\u1ec1u cao h\u00ecnh h\u1ed9p ch\u1eef nh\u1eadt, ta l\u1ea5y di\u1ec7n t\u00edch xung quanh chia cho chu vi \u0111\u00e1y<\/p>\n<p dir=\"ltr\">\u2192 c = S(xung quanh) : P (\u0111\u00e1y)<\/p>\n<p dir=\"ltr\">\u0110\u1ec3 t\u00ecm t\u1ed5ng hai \u0111\u00e1y h\u00ecnh h\u1ed9p ch\u1eef nh\u1eadt, ta l\u1ea5y di\u1ec7n t\u00edch xung quanh chia cho 2 r\u1ed3i chia cho chi\u1ec1u cao.<\/p>\n<p dir=\"ltr\">\u2192 (a + b) = S(xq) : 2 : h<\/p>\n<p dir=\"ltr\">\u0110\u1ec3 t\u00ecm chi\u1ec1u d\u00e0i h\u00ecnh h\u1ed9p ch\u1eef nh\u1eadt, ta l\u1ea5y di\u1ec7n t\u00edch xung quanh chia cho 2, chia cho chi\u1ec1u cao r\u1ed3i tr\u1eeb \u0111i chi\u1ec1u r\u1ed9ng.<\/p>\n<p dir=\"ltr\">\u2192 a = S(xq) : 2 : c &#8211; b<\/p>\n<p dir=\"ltr\">\u0110\u1ec3 t\u00ecm chi\u1ec1u r\u1ed9ng h\u00ecnh h\u1ed9p ch\u1eef nh\u1eadt, ta l\u1ea5y di\u1ec7n t\u00edch xung quanh chia cho 2, chia cho chi\u1ec1u cao r\u1ed3i tr\u1eeb \u0111i chi\u1ec1u d\u00e0i.<\/p>\n<p dir=\"ltr\">\u2192 b = S(xq) : 2 : c &#8211; a<\/p>\n<p dir=\"ltr\">\u0110\u1ec3 t\u00ednh di\u1ec7n t\u00edch to\u00e0n ph\u1ea7n h\u00ecnh h\u1ed9p ch\u1eef nh\u1eadt: Ta l\u1ea5y di\u1ec7n t\u00edch xung quanh c\u1ed9ng di\u1ec7n t\u00edch hai \u0111\u00e1y.<\/p>\n<p dir=\"ltr\">\u2192 Stp = S(xq) + S (2\u0111\u00e1y) Ho\u1eb7c: Stp = (a + b ) x 2 x c + a x b x 2<\/p>\n<p dir=\"ltr\">\u0110\u1ec3 t\u00ecm di\u1ec7n t\u00edch \u0111\u00e1y h\u00ecnh h\u1ed9p ch\u1eef nh\u1eadt ta l\u1ea5y chi\u1ec1u d\u00e0i nh\u00e2n v\u1edbi chi\u1ec1u r\u1ed9ng.<\/p>\n<p dir=\"ltr\">\u2192 S(\u0111\u00e1y) = a x b<\/p>\n<p dir=\"ltr\">\u0110\u1ec3 t\u00ecm chi\u1ec1u d\u00e0i h\u00ecnh h\u1ed9p ch\u1eef nh\u1eadt, ta l\u1ea5y di\u1ec7n t\u00edch \u0111\u00e1y chia cho chi\u1ec1u r\u1ed9ng.<\/p>\n<p dir=\"ltr\">\u2192 a = S(\u0111\u00e1y) : b<\/p>\n<p dir=\"ltr\">\u0110\u1ec3 t\u00ecm chi\u1ec1u r\u1ed9ng h\u00ecnh h\u1ed9p ch\u1eef nh\u1eadt, ta l\u1ea5y di\u1ec7n t\u00edch \u0111\u00e1y chia cho chi\u1ec1u d\u00e0i.<\/p>\n<p dir=\"ltr\">\u2192 b = S (\u0111\u00e1y) : a<\/p>\n<p dir=\"ltr\">C\u00f4ng th\u1ee9c t\u00ednh th\u1ec3 t\u00edch h\u00ecnh h\u1ed9p ch\u1eef nh\u1eadt: ta l\u1ea5y chi\u1ec1u d\u00e0i nh\u00e2n v\u1edbi chi\u1ec1u r\u1ed9ng r\u1ed3i nh\u00e2n v\u1edbi chi\u1ec1u cao (c\u00f9ng m\u1ed9t \u0111\u01a1n v\u1ecb \u0111o).<\/p>\n<p dir=\"ltr\">\u2192 V = a x b x c<\/p>\n<p dir=\"ltr\">\u0110\u1ec3 t\u00ecm chi\u1ec1u d\u00e0i h\u00ecnh h\u1ed9p ch\u1eef nh\u1eadt, ta l\u1ea5y th\u1ec3 t\u00edch chia cho chi\u1ec1u r\u1ed9ng r\u1ed3i chia ti\u1ebfp cho chi\u1ec1u cao.<\/p>\n<p dir=\"ltr\">\u2192 a = V : b : c<\/p>\n<p dir=\"ltr\">\u0110\u1ec3 t\u00ecm chi\u1ec1u r\u1ed9ng, ta l\u1ea5y th\u1ec3 t\u00edch chia cho chi\u1ec1u d\u00e0i r\u1ed3i chia ti\u1ebfp cho chi\u1ec1u cao.<\/p>\n<p dir=\"ltr\">\u2192 b = V : a : c<\/p>\n<p dir=\"ltr\">\u0110\u1ec3 t\u00ecm chi\u1ec1u cao, ta l\u1ea5y th\u1ec3 t\u00edch chia cho chi\u1ec1u d\u00e0i r\u1ed3i chia ti\u1ebfp cho chi\u1ec1u r\u1ed9ng.<\/p>\n<p dir=\"ltr\">\u2192 c = V : a : b<\/p>\n<p dir=\"ltr\">ho\u1eb7c l\u1ea5y th\u1ec3 t\u00edch chia cho di\u1ec7n t\u00edch \u0111\u00e1y<\/p>\n<p dir=\"ltr\">\u2192 c = V : S(\u0111\u00e1y)<\/p>\n<p dir=\"ltr\"><img decoding=\"async\" class=\"lazyload\" src=\"https:\/\/external-content.duckduckgo.com\/iu\/?u=https:\/\/vnmedia2.monkeyuni.net\/upload\/web\/img\/cac-quy-tac-hoc-toan-lop-4-15.jpg\" alt=\"\u0110\u1eb7c \u0111i\u1ec3m c\u1ee7a h\u00ecnh h\u1ed9p ch\u1eef nh\u1eadt. (\u1ea2nh: S\u01b0u t\u1ea7m internet)\" width=\"100%\"><\/p>\n<h4 dir=\"ltr\"><span class=\"ez-toc-section\" id=\"_Hinh_lap_phuong\"><\/span>* H\u00ecnh l\u1eadp ph\u01b0\u01a1ng<span class=\"ez-toc-section-end\"><\/span><\/h4>\n<ul>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">H\u00ecnh l\u1eadp ph\u01b0\u01a1ng c\u00f3 6 m\u1eb7t l\u00e0 c\u00e1c h\u00ecnh vu\u00f4ng b\u1eb1ng nhau.<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">C\u00f3 8 \u0111\u1ec9nh, 12 c\u1ea1nh d\u00e0i b\u1eb1ng nhau. K\u00ed hi\u1ec7u c\u1ea1nh l\u00e0 a<\/p>\n<\/li>\n<\/ul>\n<p dir=\"ltr\">C\u00f4ng th\u1ee9c t\u00ednh di\u1ec7n t\u00edch xung quanh h\u00ecnh l\u1eadp ph\u01b0\u01a1ng: Ta l\u1ea5y di\u1ec7n t\u00edch m\u1ed9t m\u1eb7t nh\u00e2n v\u1edbi 4<\/p>\n<p dir=\"ltr\">\u2192 S\u00d7q = S(1 m\u1eb7t) \u00d7 4<\/p>\n<p dir=\"ltr\">\u0110\u1ec3 t\u00ednh di\u1ec7n t\u00edch to\u00e0n ph\u1ea7n h\u00ecnh l\u1eadp ph\u01b0\u01a1ng: Ta l\u1ea5y di\u1ec7n t\u00edch m\u1ed9t m\u1eb7t nh\u00e2n v\u1edbi 6<\/p>\n<p dir=\"ltr\">\u2192 Stp = S(1 m\u1eb7t) \u00d7 6<\/p>\n<p dir=\"ltr\">\u0110\u1ec3 t\u00ednh di\u1ec7n t\u00edch m\u1ed9t m\u1eb7t ta l\u1ea5y di\u1ec7n t\u00edch xung quanh chia cho 4 ho\u1eb7c di\u1ec7n t\u00edch to\u00e0n ph\u1ea7n chia cho 6.<\/p>\n<p dir=\"ltr\">\u2192 S(1 m\u1eb7t) = S\u00d7q : 4 ho\u1eb7c S(1 m\u1eb7t) = Stp : 6<\/p>\n<p dir=\"ltr\">\u0110\u1ec3 t\u00ednh 1 c\u1ea1nh h\u00ecnh l\u1eadp ph\u01b0\u01a1ng, ta t\u00ecm xem m\u1ed9t s\u1ed1 n\u00e0o \u0111\u00f3 nh\u00e2n v\u1edbi ch\u00ednh n\u00f3 b\u1eb1ng di\u1ec7n t\u00edch m\u1ed9t m\u1eb7t, th\u00ec \u0111\u00f3 l\u00e0 c\u1ea1nh.<\/p>\n<p dir=\"ltr\">C\u00f4ng th\u1ee9c t\u00ednh th\u1ec3 t\u00edch h\u00ecnh l\u1eadp ph\u01b0\u01a1ng: Ta l\u1ea5y c\u1ea1nh nh\u00e2n v\u1edbi c\u1ea1nh r\u1ed3i nh\u00e2n v\u1edbi c\u1ea1nh.<\/p>\n<p dir=\"ltr\">\u2192 V = a \u00d7 a \u00d7 a<\/p>\n<p dir=\"ltr\">\u0110\u1ec3 t\u00ednh 1 c\u1ea1nh h\u00ecnh l\u1eadp ph\u01b0\u01a1ng, ta t\u00ecm xem m\u1ed9t s\u1ed1 n\u00e0o \u0111\u00f3 nh\u00e2n v\u1edbi ch\u00ednh n\u00f3 r\u1ed3i nh\u00e2n ti\u1ebfp v\u1edbi n\u00f3 b\u1eb1ng th\u1ec3 t\u00edch, th\u00ec \u0111\u00f3 l\u00e0 c\u1ea1nh.<\/p>\n<p dir=\"ltr\"><img decoding=\"async\" class=\"lazyload\" src=\"https:\/\/external-content.duckduckgo.com\/iu\/?u=https:\/\/vnmedia2.monkeyuni.net\/upload\/web\/img\/cac-quy-tac-hoc-toan-lop-4-16.jpg\" alt=\"C\u00e1c c\u00f4ng th\u1ee9c v\u1ec1 h\u00ecnh l\u1eadp ph\u01b0\u01a1ng c\u0169ng kh\u00e1 \u0111a d\u1ea1ng\" width=\"100%\"><\/p>\n<table style=\"border-collapse: collapse;width: 100%;background-color: #fbeeb8\" border=\"1\">\n<tr>\n<td style=\"width: 98.5189%\">\n<p style=\"text-align: center\">Ch\u1ec9 v\u1edbi kho\u1ea3ng 10 ph\u00fat h\u1ecdc ti\u1ebfng Anh m\u1ed7i ng\u00e0y c\u00f9ng Shining Home &#8211; Gia \u0111\u00ecnh Anh Ng\u1eef, con c\u00f3 th\u1ec3 t\u00edch l\u0169y 1.000 t\u1eeb v\u1ef1ng ti\u1ebfng Anh\/ n\u0103m.\u00a0<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" style=\"margin-left: auto;margin-right: auto\" class=\"lazyload\" src=\"https:\/\/external-content.duckduckgo.com\/iu\/?u=https:\/\/vnmedia2.monkeyuni.net\/upload\/web\/img\/timhieungay.png\" alt=\"\" width=\"200\" height=\"41\"><\/p>\n<\/td>\n<\/tr>\n<\/table>\n<h3 dir=\"ltr\"><span class=\"ez-toc-section\" id=\"Cac_quy_tac_toan_hoc_lop_4_ve_phan_so_va_cac_phep_tinh_phan_so\"><\/span>C\u00e1c quy t\u1eafc to\u00e1n h\u1ecdc l\u1edbp 4 v\u1ec1 ph\u00e2n s\u1ed1 v\u00e0 c\u00e1c ph\u00e9p t\u00ednh ph\u00e2n s\u1ed1<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p dir=\"ltr\">Ph\u00e2n s\u1ed1 c\u0169ng l\u00e0 ph\u1ea7n ki\u1ebfn th\u1ee9c quan tr\u1ecdng trong ch\u01b0\u01a1ng tr\u00ecnh to\u00e1n l\u1edbp 4, n\u1ebfu kh\u00f4ng n\u1eafm r\u00f5 c\u00e1c quy t\u1eafc b\u00e9 s\u1ebd kh\u00f3 chinh ph\u1ee5c \u0111\u01b0\u1ee3c d\u1ea1ng to\u00e1n n\u00e0y.<\/p>\n<h4 dir=\"ltr\"><span class=\"ez-toc-section\" id=\"_Khai_niem_phan_so\"><\/span>* Kh\u00e1i ni\u1ec7m ph\u00e2n s\u1ed1<span class=\"ez-toc-section-end\"><\/span><\/h4>\n<p dir=\"ltr\">Ph\u00e2n s\u1ed1 l\u00e0 s\u1ed1 \u0111\u01b0\u1ee3c c\u1ea5u t\u1ea1o g\u1ed3m t\u1eed s\u1ed1 v\u00e0 m\u1eabu s\u1ed1. Trong \u0111\u00f3, t\u1eed s\u1ed1 ch\u00ednh l\u00e0 s\u1ed1 t\u1ef1 nhi\u00ean n\u1eb1m tr\u00ean d\u1ea5u g\u1ea1ch. M\u1eabu s\u1ed1 l\u00e0 s\u1ed1 t\u1ef1 nhi\u00ean kh\u00e1c 0 vi\u1ebft d\u01b0\u1edbi d\u1ea5u g\u1ea1ch.<\/p>\n<p dir=\"ltr\">M\u1ed9t s\u1ed1 t\u00ednh ch\u1ea5t c\u01a1 b\u1ea3n c\u1ee7a ph\u00e2n s\u1ed1:<\/p>\n<ul>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">T\u1ea5t c\u1ea3 s\u1ed1 t\u1ef1 nhi\u00ean \u0111\u1ec3 c\u00f3 th\u1ec3 vi\u1ebft \u0111\u01b0\u1ee3c d\u01b0\u1edbi d\u1ea1ng ph\u00e2n s\u1ed1 c\u00f3 t\u1eed s\u1ed1 l\u00e0 s\u1ed1 t\u1ef1 nhi\u00ean \u0111\u00f3 v\u00e0 m\u1eabu s\u1ed1 b\u1eb1ng 1.<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">S\u1ed1 1 c\u00f3 th\u1ec3 vi\u1ebft th\u00e0nh d\u1ea1ng ph\u00e2n s\u1ed1 c\u00f3 t\u1eed s\u1ed1 v\u00e0 m\u1eabu s\u1ed1 b\u1eb1ng nhau v\u00e0 kh\u00e1c 1.<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">S\u1ed1 0 c\u00f3 th\u1ec3 vi\u1ebft th\u00e0nh d\u1ea1ng ph\u00e2n s\u1ed1 c\u00f3 t\u1eed s\u1ed1 l\u00e0 0 v\u00e0 m\u1eabu s\u1ed1 kh\u00e1c 0.<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">N\u1ebfu nh\u00e2n c\u1ea3 t\u1eed s\u1ed1 v\u00e0 m\u1eabu s\u1ed1 c\u1ee7a m\u1ed9t ph\u00e2n s\u1ed1 b\u1ea5t k\u1ef3 v\u1edbi c\u00f9ng m\u1ed9t s\u1ed1 t\u1ef1 nhi\u00ean kh\u00e1c 0 th\u00ec ta \u0111\u01b0\u1ee3c m\u1ed9t ph\u00e2n s\u1ed1 m\u1edbi b\u1eb1ng ph\u00e2n s\u1ed1 \u0111\u00e3 cho.<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">N\u1ebfu chia c\u1ea3 t\u1eed s\u1ed1 v\u00e0 m\u1eabu s\u1ed1 c\u1ee7a m\u1ed9t ph\u00e2n s\u1ed1 b\u1ea5t k\u1ef3 v\u1edbi c\u00f9ng m\u1ed9t s\u1ed1 t\u1ef1 nhi\u00ean kh\u00e1c 0 th\u00ec ta \u0111\u01b0\u1ee3c m\u1ed9t ph\u00e2n s\u1ed1 m\u1edbi b\u1eb1ng ph\u00e2n s\u1ed1 \u0111\u00e3 cho.<\/p>\n<\/li>\n<\/ul>\n<p dir=\"ltr\"><img decoding=\"async\" class=\"lazyload\" src=\"https:\/\/external-content.duckduckgo.com\/iu\/?u=https:\/\/vnmedia2.monkeyuni.net\/upload\/web\/img\/cac-quy-tac-hoc-toan-lop-4-17.jpg\" alt=\"Ki\u1ebfn th\u1ee9c ph\u00e2n s\u1ed1 to\u00e1n l\u1edbp 4 kh\u00e1 \u0111a d\u1ea1ng. (\u1ea2nh: S\u01b0u t\u1ea7m internet)\" width=\"100%\"><\/p>\n<h4 dir=\"ltr\"><span class=\"ez-toc-section\" id=\"_So_sanh_cac_phan_so\"><\/span>* So s\u00e1nh c\u00e1c ph\u00e2n s\u1ed1<span class=\"ez-toc-section-end\"><\/span><\/h4>\n<p dir=\"ltr\">\u0110\u1ec3 so s\u00e1nh ph\u00e2n s\u1ed1, c\u00e1c em c\u1ea7n l\u01b0u \u00fd:<\/p>\n<p dir=\"ltr\">1. So s\u00e1nh c\u00e1c ph\u00e2n s\u1ed1 c\u00f3 c\u00f9ng m\u1eabu s\u1ed1<\/p>\n<ul>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">Ph\u00e2n s\u1ed1 n\u00e0o c\u00f3 t\u1eed s\u1ed1 nh\u1ecf h\u01a1n th\u00ec ph\u00e2n s\u1ed1 \u0111\u00f3 s\u1ebd nh\u1ecf h\u01a1n.<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">Ph\u00e2n s\u1ed1 n\u00e0o c\u00f3 t\u1eed s\u1ed1 l\u1edbn h\u01a1n th\u00ec ph\u00e2n s\u1ed1 \u0111\u00f3 s\u1ebd l\u1edbn h\u01a1n.<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">N\u1ebfu hai ph\u00e2n s\u1ed1 c\u00f3 t\u1eed s\u1ed1 b\u1eb1ng nhau th\u00ec hai ph\u00e2n s\u1ed1 \u0111\u00f3 s\u1ebd b\u1eb1ng nhau.<\/p>\n<\/li>\n<\/ul>\n<p dir=\"ltr\">2. So s\u00e1nh c\u00e1c ph\u00e2n s\u1ed1 c\u00f3 c\u00f9ng t\u1eed s\u1ed1<\/p>\n<ul>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">Ph\u00e2n s\u1ed1 n\u00e0o c\u00f3 m\u1eabu s\u1ed1 nh\u1ecf h\u01a1n th\u00ec ph\u00e2n s\u1ed1 \u0111\u00f3 s\u1ebd l\u1edbn h\u01a1n.<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">Ph\u00e2n s\u1ed1 n\u00e0o c\u00f3 m\u1eabu s\u1ed1 l\u1edbn h\u01a1n th\u00ec ph\u00e2n s\u1ed1 \u0111\u00f3 nh\u1ecf s\u1ebd h\u01a1n.<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">N\u1ebfu hai ph\u00e2n s\u1ed1 c\u00f3 m\u1eabu s\u1ed1 b\u1eb1ng nhau th\u00ec hai ph\u00e2n s\u1ed1 \u0111\u00f3 s\u1ebd b\u1eb1ng nhau.<\/p>\n<\/li>\n<\/ul>\n<p dir=\"ltr\">3. So s\u00e1nh c\u00e1c ph\u00e2n s\u1ed1 kh\u00e1c m\u1eabu s\u1ed1<\/p>\n<p dir=\"ltr\">\u0110\u1ec3 so s\u00e1nh hai ph\u00e2n s\u1ed1 kh\u00e1c m\u1eabu s\u1ed1 th\u00ec c\u1ea7n ph\u1ea3i quy \u0111\u1ed3ng m\u1eabu s\u1ed1 hai ph\u00e2n s\u1ed1 \u0111\u00f3 r\u1ed3i so s\u00e1nh c\u00e1c t\u1eed s\u1ed1 c\u1ee7a hai ph\u00e2n s\u1ed1 m\u1edbi.<\/p>\n<h4 dir=\"ltr\"><span class=\"ez-toc-section\" id=\"_Cac_phep_tinh_phan_so\"><\/span>* C\u00e1c ph\u00e9p t\u00ednh ph\u00e2n s\u1ed1<span class=\"ez-toc-section-end\"><\/span><\/h4>\n<p dir=\"ltr\">C\u0169ng t\u01b0\u01a1ng t\u1ef1 nh\u01b0 c\u00e1c s\u1ed1 t\u1ef1 nhi\u00ean, v\u1edbi ph\u00e2n s\u1ed1 c\u0169ng s\u1ebd c\u00f3 nh\u1eefng ph\u00e9p t\u00ednh c\u01a1 b\u1ea3n sau:<\/p>\n<p dir=\"ltr\">1. Ph\u00e9p c\u1ed9ng ph\u00e2n s\u1ed1<\/p>\n<ul>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">\u0110\u1ec3 c\u1ed9ng 2 ph\u1ea7n s\u1ed1 c\u00f9ng m\u1eabu, ta ch\u1ec9 c\u1ea7n c\u1ed9ng t\u1eed v\u1edbi t\u1eed s\u1ed1 v\u00e0 gi\u1eef nguy\u00ean m\u1eabu s\u1ed1.<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">\u0110\u1ec3 c\u1ed9ng 2 ph\u00e2n s\u1ed1 kh\u00e1c m\u1eabu, ta quy \u0111\u1ed3ng m\u1eabu s\u1ed1 c\u1ee7a hai ph\u00e2n s\u1ed1 r\u1ed3i ti\u1ebfn h\u00e0nh c\u1ed9ng hai ph\u00e2n s\u1ed1 m\u1edbi v\u1edbi nhau.<\/p>\n<\/li>\n<\/ul>\n<p dir=\"ltr\">2. Ph\u00e9p tr\u1eeb ph\u00e2n s\u1ed1<\/p>\n<ul>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">\u0110\u1ec3 c\u1ed9ng 2 ph\u1ea7n s\u1ed1 c\u00f9ng m\u1eabu, ta ch\u1ec9 c\u1ea7n tr\u1eeb t\u1eed s\u1ed1 ph\u00e2n s\u1ed1 th\u1ee9 nh\u1ea5t cho t\u1eed s\u1ed1 c\u1ee7a ph\u00e2n s\u1ed1 th\u1ee9 2 v\u00e0 gi\u1eef nguy\u00ean m\u1eabu s\u1ed1.<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">\u0110\u1ec3 tr\u1eeb 2 ph\u00e2n s\u1ed1 kh\u00e1c m\u1eabu, ta quy \u0111\u1ed3ng m\u1eabu s\u1ed1 c\u1ee7a hai ph\u00e2n s\u1ed1 r\u1ed3i ti\u1ebfn h\u00e0nh tr\u1eeb hai ph\u00e2n s\u1ed1 m\u1edbi v\u1edbi nhau.<\/p>\n<\/li>\n<\/ul>\n<p dir=\"ltr\">3. Ph\u00e9p nh\u00e2n ph\u00e2n s\u1ed1<\/p>\n<p dir=\"ltr\">\u0110\u1ec3 nh\u00e2n hai ph\u00e2n s\u1ed1, ta l\u1ea5y t\u1eed s\u1ed1 ph\u00e2n s\u1ed1 th\u1ee9 nh\u1ea5t nh\u00e2n v\u1edbi t\u1eed s\u1ed1 th\u1ee9 hai v\u00e0 m\u1eabu s\u1ed1 ph\u00e2n s\u1ed1 th\u1ee9 nh\u1ea5t nh\u00e2n v\u1edbi m\u1eabu s\u1ed1 ph\u00e2n s\u1ed1 th\u1ee9 hai.<\/p>\n<p dir=\"ltr\">4. Ph\u00e9p chia ph\u00e2n s\u1ed1<\/p>\n<p dir=\"ltr\">\u0110\u1ec3 chia hai ph\u00e2n s\u1ed1, l\u00e0 l\u1ea5y ph\u00e2n s\u1ed1 th\u1ee9 nh\u1ea5t nh\u00e2n v\u1edbi ngh\u1ecbch \u0111\u1ea3o ph\u00e2n s\u1ed1 th\u1ee9 2. Trong \u0111\u00f3, ngh\u1ecbch \u0111\u1ea3o ph\u00e2n s\u1ed1 ch\u00ednh l\u00e0 ph\u00e2n s\u1ed1 \u0111\u1ea3o ng\u01b0\u1ee3c t\u1eed th\u00e0nh m\u1eabu v\u00e0 m\u1eabu th\u00e0nh t\u1eed.<\/p>\n<h4 dir=\"ltr\"><span class=\"ez-toc-section\" id=\"_Tim_phan_so_cua_mot_so\"><\/span>* T\u00ecm ph\u00e2n s\u1ed1 c\u1ee7a m\u1ed9t s\u1ed1<span class=\"ez-toc-section-end\"><\/span><\/h4>\n<p dir=\"ltr\">\u0110\u1ec3 t\u00ecm ph\u00e2n s\u1ed1 c\u1ee7a m\u1ed9t s\u1ed1, ta l\u1ea5y s\u1ed1 \u0111\u00f3 nh\u00e2n v\u1edbi ph\u00e2n s\u1ed1 \u0111\u00e3 cho.<\/p>\n<p dir=\"ltr\">C\u00f4ng th\u1ee9c: gi\u00e1 tr\u1ecb a\/b c\u1ee7a A = A \u00d7 a\/b<\/p>\n<p dir=\"ltr\"><em>V\u00ed d\u1ee5: Trong r\u1ed5 c\u00f3 12 qu\u1ea3 cam. H\u1ecfi 2\/3 s\u1ed1 cam trong r\u1ed5 l\u00e0 bao nhi\u00eau?<\/em><\/p>\n<p dir=\"ltr\"><em>Gi\u1ea3i<\/em><\/p>\n<p dir=\"ltr\"><em>2\/3 S\u1ed1 cam trong r\u1ed5 l\u00e0:<\/em><\/p>\n<p dir=\"ltr\"><em>12 \u00d7 2\/3 = 8 (qu\u1ea3)<\/em><\/p>\n<p dir=\"ltr\"><em>\u0110\u00e1p s\u1ed1: 8 qu\u1ea3<\/em><\/p>\n<h4 dir=\"ltr\"><span class=\"ez-toc-section\" id=\"_Tim_mot_so_biet_gia_tri_phan_so_cua_so_do\"><\/span>* T\u00ecm m\u1ed9t s\u1ed1 bi\u1ebft gi\u00e1 tr\u1ecb ph\u00e2n s\u1ed1 c\u1ee7a s\u1ed1 \u0111\u00f3<span class=\"ez-toc-section-end\"><\/span><\/h4>\n<p dir=\"ltr\">\u0110\u1ec3 m\u1ed9t s\u1ed1 khi bi\u1ebft m\u1ed9t gi\u00e1 tr\u1ecb ph\u00e2n s\u1ed1 c\u1ee7a s\u1ed1 \u0111\u00f3, ta l\u1ea5y gi\u00e1 tr\u1ecb \u0111\u00f3 chia cho ph\u00e2n s\u1ed1.<\/p>\n<p dir=\"ltr\">Gi\u00e1 tr\u1ecb a\/b c\u1ee7a A = gi\u00e1 tr\u1ecb c\u1ee7a ph\u00e2n s\u1ed1 : a\/b<\/p>\n<p dir=\"ltr\"><em>V\u00ed d\u1ee5: Cho 2\/3 s\u1ed1 cam trong r\u1ed5 cam l\u00e0 8 qu\u1ea3. H\u1ecfi r\u1ed5 cam \u0111\u00f3 c\u00f3 bao nhi\u00eau qu\u1ea3?<\/em><\/p>\n<p dir=\"ltr\"><em>Gi\u1ea3i<\/em><\/p>\n<p dir=\"ltr\"><em>S\u1ed1 cam trong r\u1ed5 l\u00e0:<\/em><\/p>\n<p dir=\"ltr\"><em>8 : 2\/3 = 12 (qu\u1ea3)<\/em><\/p>\n<p dir=\"ltr\"><em>\u0110\u00e1p s\u1ed1: 12 qu\u1ea3<\/em><\/p>\n<h3 dir=\"ltr\"><span class=\"ez-toc-section\" id=\"On_tap_tim_hai_so_khi_biet_tong_hoac_hieu_va_ti_cua_hai_so_do\"><\/span>\u00d4n t\u1eadp t\u00ecm hai s\u1ed1 khi bi\u1ebft t\u1ed5ng ho\u1eb7c hi\u1ec7u v\u00e0 t\u1ec9 c\u1ee7a hai s\u1ed1 \u0111\u00f3<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p dir=\"ltr\">M\u1ed9t trong nh\u1eefng ch\u1ee7 \u0111\u1ec1 m\u00e0 c\u00e1c em s\u1ebd h\u1ecdc trong ch\u01b0\u01a1ng tr\u00ecnh to\u00e1n l\u1edbp 4 kh\u00e1 quan tr\u1ecdng, ch\u00ednh l\u00e0 vi\u1ec7c gi\u1ea3i b\u00e0i t\u1eadp t\u00ecm 2 s\u1ed1 khi bi\u1ebft t\u1ed5ng ho\u1eb7c hi\u1ec7u v\u00e0 t\u1ec9 s\u1ed1 c\u1ee7a ch\u00fang. \u0110\u1ec3 chinh ph\u1ee5c \u0111\u01b0\u1ee3c d\u1ea1ng b\u00e0i t\u1eadp n\u00e0y, c\u00e1c em c\u1ea7n ghi nh\u1edb c\u00e1c quy t\u1eafc sau:<\/p>\n<h4 dir=\"ltr\"><span class=\"ez-toc-section\" id=\"_Tong_va_hieu\"><\/span>* T\u1ed5ng v\u00e0 hi\u1ec7u<span class=\"ez-toc-section-end\"><\/span><\/h4>\n<ul>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">S\u1ed1 b\u00e9 = (T\u1ed5ng \u2013 Hi\u1ec7u) : 2<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">S\u1ed1 l\u1edbn = (T\u1ed5ng + Hi\u1ec7u) : 2<\/p>\n<\/li>\n<\/ul>\n<p dir=\"ltr\"><em>V\u00ed d\u1ee5: T\u00ecm hai s\u1ed1 bi\u1ebft t\u1ed5ng c\u1ee7a hai s\u1ed1 \u0111\u00f3 l\u00e0 90. Hi\u1ec7u c\u1ee7a hai s\u1ed1 l\u00e0 34.<\/em><\/p>\n<p dir=\"ltr\"><em>C\u00e1ch gi\u1ea3i:<\/em><\/p>\n<p dir=\"ltr\"><em>S\u1ed1 b\u00e9 l\u00e0: (90 \u2013 34) : 2 = 28<\/em><\/p>\n<p dir=\"ltr\"><em>S\u1ed1 l\u1edbn l\u00e0: (90 + 34) : 2 = 62<\/em><\/p>\n<p dir=\"ltr\"><em>V\u1eady s\u1ed1 b\u00e9 l\u00e0 28 v\u00e0 s\u1ed1 l\u1edbn l\u00e0 62.<\/em><\/p>\n<h4 dir=\"ltr\"><span class=\"ez-toc-section\" id=\"_Tong_va_ti\"><\/span>* T\u1ed5ng v\u00e0 t\u1ec9<span class=\"ez-toc-section-end\"><\/span><\/h4>\n<p dir=\"ltr\">C\u00e1c b\u01b0\u1edbc gi\u1ea3i b\u00e0i to\u00e1n khi bi\u1ebft t\u1ed5ng v\u00e0 t\u1ec9 s\u1ed1:<\/p>\n<ul>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">B\u01b0\u1edbc 1: Ta ph\u1ea3i x\u00e1c \u0111\u1ecbnh t\u1ed5ng v\u00e0 t\u1ec9 s\u1ed1 \u0111\u00e3 cho r\u1ed3i bi\u1ec3u di\u1ec5n ch\u00fang tr\u00ean s\u01a1 \u0111\u1ed3 \u0111o\u1ea1n th\u1eb3ng, t\u00f3m t\u1eaft b\u00e0i to\u00e1n.<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">B\u01b0\u1edbc 2: D\u1ef1a v\u00e0o s\u01a1 \u0111\u1ed3 \u0111o\u1ea1n th\u1eb3ng \u0111\u1ec3 ti\u1ebfn h\u00e0nh t\u00ecm t\u1ed5ng s\u1ed1 b\u1eb1ng nhau.<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">B\u01b0\u1edbc 3: T\u00ecm gi\u00e1 tr\u1ecb ph\u1ea7n c\u1ea7n t\u00ecm trong b\u00e0i to\u00e1n<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">B\u01b0\u1edbc 4: T\u00ecm s\u1ed1 l\u1edbn (ho\u1eb7c s\u1ed1 b\u00e9)<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">B\u01b0\u1edbc 5: T\u00ecm s\u1ed1 b\u00e9 (ho\u1eb7c s\u1ed1 l\u1edbn), tr\u00ecnh b\u00e0y l\u1eddi gi\u1ea3i v\u00e0 ghi \u0111\u00e1p s\u1ed1<\/p>\n<\/li>\n<\/ul>\n<p dir=\"ltr\"><em>V\u00ed d\u1ee5: T\u00ecm hai s\u1ed1 bi\u1ebft t\u1ed5ng c\u1ee7a hai s\u1ed1 \u0111\u00f3 l\u00e0 84. T\u1ec9 s\u1ed1 c\u1ee7a hai s\u1ed1 \u0111\u00f3 l\u00e0 2\/5.<\/em><\/p>\n<p dir=\"ltr\"><em>H\u01b0\u1edbng d\u1eabn gi\u1ea3i:<\/em><\/p>\n<p dir=\"ltr\"><em>Ta c\u00f3 s\u01a1 \u0111\u1ed3 nh\u01b0 sau:<\/em><\/p>\n<p dir=\"ltr\"><em>T\u1ed5ng s\u1ed1 ph\u1ea7n b\u1eb1ng nhau l\u00e0: 2 + 5 = 7 (ph\u1ea7n)<\/em><\/p>\n<p dir=\"ltr\"><em>Gi\u00e1 tr\u1ecb c\u1ee7a m\u1ed9t ph\u1ea7n l\u00e0: 84 : 7 = 12<\/em><\/p>\n<p dir=\"ltr\"><em>S\u1ed1 b\u00e9 l\u00e0: 12 x 2 = 24<\/em><\/p>\n<p dir=\"ltr\"><em>S\u1ed1 l\u1edbn l\u00e0: 12 x 5 = 60<\/em><\/p>\n<p dir=\"ltr\"><em>V\u1eady s\u1ed1 b\u00e9 l\u00e0 24 v\u00e0 s\u1ed1 l\u1edbn l\u00e0 60.<\/em><\/p>\n<h4 dir=\"ltr\"><span class=\"ez-toc-section\" id=\"_Hieu_va_ti\"><\/span>* Hi\u1ec7u v\u00e0 t\u1ec9<span class=\"ez-toc-section-end\"><\/span><\/h4>\n<p dir=\"ltr\">C\u00e1c b\u01b0\u1edbc gi\u1ea3i b\u00e0i to\u00e1n khi bi\u1ebft hi\u1ec7u v\u00e0 t\u1ec9 s\u1ed1:<\/p>\n<ul>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">B\u01b0\u1edbc 1: X\u00e1c \u0111\u1ecbnh gi\u00e1 tr\u1ecb hi\u1ec7u v\u00e0 t\u1ec9 s\u1ed1 c\u1ee7a b\u00e0i to\u00e1n, r\u1ed3i bi\u1ec3u di\u1ec5n ch\u00fang tr\u00ean s\u01a1 \u0111\u1ed3 \u0111o\u1ea1n th\u1eb3ng v\u00e0 t\u00f3m t\u1eaft b\u00e0i to\u00e1n.<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">B\u01b0\u1edbc 2: D\u1ef1a v\u00e0o s\u01a1 \u0111\u1ed3 \u0111o\u1ea1n th\u1eb3ng \u0111\u1ec3 t\u00ecm hi\u1ec7u s\u1ed1 ph\u1ea7n b\u1eb1ng nhau<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">B\u01b0\u1edbc 3: T\u00ecm gi\u00e1 tr\u1ecb m\u1ed9t ph\u1ea7n trong b\u00e0i to\u00e1n<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">B\u01b0\u1edbc 4: T\u00ecm s\u1ed1 l\u1edbn (ho\u1eb7c s\u1ed1 b\u00e9)<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">B\u01b0\u1edbc 5: T\u00ecm s\u1ed1 b\u00e9 (ho\u1eb7c s\u1ed1 l\u1edbn), tr\u00ecnh b\u00e0y l\u1eddi gi\u1ea3i v\u00e0 ghi \u0111\u00e1p s\u1ed1<\/p>\n<\/li>\n<\/ul>\n<p dir=\"ltr\"><em>V\u00ed d\u1ee5: T\u00ecm hai s\u1ed1 b\u00e9 hi\u1ec7u c\u1ee7a hai s\u1ed1 \u0111\u00f3 l\u00e0 56. T\u1ec9 s\u1ed1 c\u1ee7a hai s\u1ed1 \u0111\u00f3 l\u00e0 \u2157.\u00a0<\/em><\/p>\n<p dir=\"ltr\"><em>H\u01b0\u1edbng d\u1eabn gi\u1ea3i:<\/em><\/p>\n<p dir=\"ltr\"><em>Ta c\u00f3 s\u01a1 \u0111\u1ed3 \u0111o\u1ea1n th\u1eb3ng nh\u01b0 sau:<\/em><\/p>\n<p dir=\"ltr\"><em>Hi\u1ec7u s\u1ed1 ph\u1ea7n b\u1eb1ng nhau l\u00e0: 5 \u2013 3 = 2 (ph\u1ea7n)<\/em><\/p>\n<p dir=\"ltr\"><em>Gi\u00e1 tr\u1ecb c\u1ee7a m\u1ed9t ph\u1ea7n l\u00e0: 56 : 2 = 28<\/em><\/p>\n<p dir=\"ltr\"><em>S\u1ed1 b\u00e9 l\u00e0: 28 x 3 = 84<\/em><\/p>\n<p dir=\"ltr\"><em>S\u1ed1 l\u1edbn l\u00e0: 28 x 5 = 140<\/em><\/p>\n<p dir=\"ltr\"><em>V\u1eady s\u1ed1 b\u00e9 l\u00e0 84 v\u00e0 s\u1ed1 l\u1edbn l\u00e0 140.<\/em><\/p>\n<p dir=\"ltr\">\n<h2 dir=\"ltr\"><span class=\"ez-toc-section\" id=\"Bi_quyet_hoc_cac_quy_tac_toan_hoc_lop_4_hieu_qua\"><\/span>B\u00ed quy\u1ebft h\u1ecdc c\u00e1c quy t\u1eafc to\u00e1n h\u1ecdc l\u1edbp 4 hi\u1ec7u qu\u1ea3<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p dir=\"ltr\">C\u00e1c quy t\u1eafc, c\u00f4ng th\u1ee9c to\u00e1n h\u1ecdc l\u1edbp 4 c\u01a1 b\u1ea3n kh\u00e1 nhi\u1ec1u. N\u00ean \u0111\u1ec3 gi\u00fap b\u00e9 h\u1ecdc t\u1ed1t nh\u1eefng ki\u1ebfn th\u1ee9c n\u00e0y, d\u01b0\u1edbi \u0111\u00e2y l\u00e0 m\u1ed9t s\u1ed1 b\u00ed quy\u1ebft m\u00e0 ph\u1ee5 huynh c\u00f3 th\u1ec3 tham kh\u1ea3o th\u00eam \u0111\u1ec3 h\u1ed7 tr\u1ee3 tr\u1ebb:<\/p>\n<p dir=\"ltr\"><img decoding=\"async\" class=\"lazyload\" src=\"https:\/\/external-content.duckduckgo.com\/iu\/?u=https:\/\/vnmedia2.monkeyuni.net\/upload\/web\/img\/cac-quy-tac-hoc-toan-lop-4-18.jpg\" alt=\"S\u01a1 \u0111\u1ed3 t\u01b0 duy to\u00e1n l\u1edbp 4. (\u1ea2nh: S\u01b0u t\u1ea7m internet)\" width=\"100%\"><\/p>\n<ul>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">H\u1ecdc t\u1edbi \u0111\u00e2u ch\u1eafc \u0111\u1ebfn \u0111\u00f3: Thay v\u00ec cho b\u00e9 h\u1ecdc qu\u00e1 nhi\u1ec1u, b\u1ed1 m\u1eb9 n\u00ean \u0111\u1ea3m b\u1ea3o con h\u1ecdc ph\u1ea7n ki\u1ebfn th\u1ee9c n\u00e0o ph\u1ea3i ch\u1eafc ch\u1eafn ph\u1ea7n \u0111\u00f3. N\u1ebfu b\u00e9 qu\u00ean hay g\u1eb7p kh\u00f3 kh\u0103n ph\u1ea7n n\u00e0o th\u00ec ph\u1ee5 huynh c\u1ea7n h\u01b0\u1edbng d\u1eabn, c\u1ee7ng c\u1ed1 l\u1ea1i k\u1ecbp th\u1eddi.<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">H\u1ecdc to\u00e1n l\u1edbp 4 theo s\u01a1 \u0111\u1ed3 t\u01b0 duy: \u0110\u00e2y l\u00e0 ph\u01b0\u01a1ng ph\u00e1p \u0111\u01b0\u1ee3c nhi\u1ec1u gi\u00e1o vi\u00ean khuy\u1ebfn kh\u00edch h\u1ecdc sinh \u00e1p d\u1ee5ng. \u0110\u1ec3 gi\u00fap b\u00e9 d\u1ec5 d\u00e0ng ti\u1ebfp thu, ghi nh\u1edb v\u00e0 t\u01b0 duy t\u1ed1t h\u01a1n khi h\u1ecdc to\u00e1n th\u00ec ph\u1ee5 huynh c\u00f3 th\u1ec3 h\u01b0\u1edbng d\u1eabn b\u00e9 v\u1ebd s\u01a1 \u0111\u1ed3 t\u01b0 duy t\u1eebng ph\u1ea7n ki\u1ebfn th\u1ee9c v\u00e0 \u00f4n luy\u1ec7n theo t\u1eebng nh\u00e1nh s\u01a1 \u0111\u1ed3 ri\u00eang s\u1ebd hi\u1ec7u qu\u1ea3 h\u01a1n.<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">T\u00edch c\u1ef1c luy\u1ec7n t\u1eadp, th\u1ef1c h\u00e0nh th\u01b0\u1eddng xuy\u00ean: B\u00ean c\u1ea1nh vi\u1ec7c n\u1eafm ch\u1eafc l\u00fd thuy\u1ebft, ph\u1ee5 huynh n\u00ean khuy\u1ebfn kh\u00edch, y\u00eau c\u1ea7u b\u00e9 th\u1ef1c h\u00e0nh nhi\u1ec1u h\u01a1n t\u1eeb l\u00e0m b\u00e0i t\u1eadp trong SGK, s\u00e1ch b\u00e0i t\u1eadp, t\u00ecm hi\u1ec3u th\u00eam nhi\u1ec1u ki\u1ebfn th\u1ee9c tr\u00ean internet, luy\u1ec7n \u0111\u1ec1 thi, \u1ee9ng d\u1ee5ng trong th\u1ef1c ti\u1ec5n, ch\u01a1i tr\u00f2 ch\u01a1i\u2026 Qua \u0111\u00f3 s\u1ebd gi\u00fap n\u00e2ng cao hi\u1ec7u qu\u1ea3 ti\u1ebfp thu, ghi nh\u1edb v\u00e0 t\u01b0 duy h\u1ecdc to\u00e1n t\u1ed1t h\u01a1n.<\/p>\n<\/li>\n<li dir=\"ltr\">\n<p dir=\"ltr\" role=\"presentation\">X\u00e2y d\u1ef1ng n\u1ec1n t\u1ea3ng to\u00e1n h\u1ecdc v\u1eefng ch\u1eafc c\u00f9ng Shining Home &#8211; Gia \u0111\u00ecnh Anh Ng\u1eef Math: \u0110\u00e2y l\u00e0 \u1ee9ng d\u1ee5ng d\u1ea1y to\u00e1n song ng\u1eef d\u00e0nh cho tr\u1ebb m\u1ea7m non v\u00e0 ti\u1ec3u h\u1ecdc, v\u1edbi h\u01a1n 400 b\u00e0i gi\u1ea3ng b\u00e1m s\u00e1t ch\u01b0\u01a1ng tr\u00ecnh GDPT m\u1edbi nh\u1ea5t c\u1ee7a B\u1ed9 \u0111\u01b0a ra, c\u00f9ng v\u1edbi h\u01a1n 60 ch\u1ee7 \u0111\u1ec1 to\u00e1n, 4 c\u1ea5p \u0111\u1ed9 t\u1eeb d\u1ec5 \u0111\u1ebfn kh\u00f3 s\u1ebd gi\u00fap b\u00e9 d\u1ec5 d\u00e0ng ti\u1ebfp thu \u0111\u01b0\u1ee3c v\u1edbi nh\u1eefng ki\u1ebfn th\u1ee9c theo ph\u01b0\u01a1ng ph\u00e1p hi\u1ec7n \u0111\u1ea1i h\u01a1n. \u0110\u1ed3ng th\u1eddi, t\u1ea5t c\u1ea3 b\u00e0i gi\u1ea3ng \u0111\u1ec1u bi\u00ean so\u1ea1n d\u01b0\u1edbi d\u1ea1ng video, h\u00ecnh \u1ea3nh ho\u1ea1t ho\u1ea1 ng\u1ed9 ngh\u0129nh, k\u1ebft h\u1ee3p c\u00f9ng v\u1edbi \u0111a d\u1ea1ng tr\u00f2 ch\u01a1i t\u01b0\u01a1ng t\u00e1c gi\u00fap b\u00e9 v\u1eeba ch\u01a1i, v\u1eeba h\u1ecdc hi\u1ec7u qu\u1ea3 h\u01a1n. Ch\u01b0a k\u1ec3, Shining Home &#8211; Gia \u0111\u00ecnh Anh Ng\u1eef Math c\u00f2n x\u00e2y d\u1ef1ng nhi\u1ec1u t\u00ednh n\u0103ng h\u1ed7 tr\u1ee3 b\u00e9 h\u1ecdc to\u00e1n m\u1ed9t c\u00e1ch b\u00e0i b\u1ea3n h\u01a1n, b\u1ed1 m\u1eb9 d\u1ec5 d\u00e0ng theo d\u00f5i v\u00e0 qu\u1ea3n l\u00fd n\u0103ng l\u1ef1c h\u1ecdc t\u1eadp c\u1ee7a b\u00e9 hi\u1ec7u qu\u1ea3 th\u00f4ng qua app.<\/p>\n<\/li>\n<\/ul>\n<p dir=\"ltr\">\u0110\u1ec3 hi\u1ec3u r\u00f5 h\u01a1n v\u1ec1 Shining Home &#8211; Gia \u0111\u00ecnh Anh Ng\u1eef Math, qu\u00fd ph\u1ee5 huynh c\u00f3 th\u1ec3 \u0111\u0103ng k\u00fd \u0111\u1ec3 nh\u1eadn \u0111\u01b0\u1ee3c t\u01b0 v\u1ea5n mi\u1ec5n ph\u00ed ho\u1eb7c theo d\u00f5i video sau:<\/p>\n<p dir=\"ltr\">\u00a0<img loading=\"lazy\" decoding=\"async\" style=\"margin-left: auto;margin-right: auto\" class=\"lazyload\" src=\"https:\/\/external-content.duckduckgo.com\/iu\/?u=https:\/\/vnmedia.monkeyuni.net\/upload\/web\/img\/button_dang-ky-ngay-1.png\" alt=\"\" width=\"200\" height=\"27\"><\/p>\n<p dir=\"ltr\" style=\"text-align: center\"><iframe loading=\"lazy\" title=\"Gi\u1edbi thi\u1ec7u \u1ee9ng d\u1ee5ng Monkey Math\" width=\"1020\" height=\"574\" src=\"https:\/\/www.youtube.com\/embed\/7DsjpvHFrOs?feature=oembed\" frameborder=\"0\" allow=\"accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share\" referrerpolicy=\"strict-origin-when-cross-origin\" allowfullscreen><\/iframe><\/p>\n<h2 dir=\"ltr\"><span class=\"ez-toc-section\" id=\"Ket_luan\"><\/span>K\u1ebft lu\u1eadn<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<\/p>\n<p dir=\"ltr\">Tr\u00ean \u0111\u00e2y l\u00e0 t\u1ed5ng h\u1ee3p c\u00e1c quy t\u1eafc to\u00e1n h\u1ecdc l\u1edbp 4 \u0111\u1ec3 ph\u1ee5 huynh v\u00e0 c\u00e1c b\u00e9 tham kh\u1ea3o. \u0110\u00e2y \u0111\u1ec1u l\u00e0 nh\u1eefng quy t\u1eafc c\u01a1 b\u1ea3n nh\u01b0ng quan tr\u1ecdng, kh\u00f4ng ch\u1ec9 h\u1ecdc \u1edf l\u1edbp 4 m\u00e0 c\u00e1c l\u1edbp cao h\u01a1n hay th\u1ef1c t\u1ebf v\u1eabn s\u1eed d\u1ee5ng \u0111\u1ebfn. V\u1eady n\u00ean, ph\u1ee5 huynh h\u00e3y c\u00f9ng con em m\u00ecnh c\u00f9ng nhau h\u1ecdc t\u1eadp, \u00f4n luy\u1ec7n \u0111\u1ec3 chinh ph\u1ee5c m\u00f4n to\u00e1n m\u1ed9t c\u00e1ch hi\u1ec7u qu\u1ea3 nh\u1ea5t nh\u00e9.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>C\u00e1c quy t\u1eafc to\u00e1n h\u1ecdc l\u1edbp 4 c\u1ef1c k\u1ef3 \u0111a d\u1ea1ng, tu\u1ef3 thu\u1ed9c v\u00e0o t\u1eebng ph\u1ea7n ki\u1ebfn th\u1ee9c \u0111\u1ec1u s\u1ebd c\u00f3 nh\u1eefng c\u00f4ng th\u1ee9c ri\u00eang. V\u1eady n\u00ean, n\u1ed9i dung b\u00e0i vi\u1ebft sau \u0111\u00e2y Shining Home &#8211; Gia \u0111\u00ecnh Anh Ng\u1eef t\u1ed5ng h\u1ee3p \u0111\u1ea7y \u0111\u1ee7 c\u00e1c quy t\u1eafc to\u00e1n l\u1edbp 4 \u0111\u1ec3 c\u00e1c em v\u00e0 ph\u1ee5&#8230;<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[100],"tags":[],"class_list":["post-14874","post","type-post","status-publish","format-standard","hentry","category-kien-thuc"],"_links":{"self":[{"href":"https:\/\/www.ckconitsha.com\/vn\/wp-json\/wp\/v2\/posts\/14874","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.ckconitsha.com\/vn\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.ckconitsha.com\/vn\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.ckconitsha.com\/vn\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.ckconitsha.com\/vn\/wp-json\/wp\/v2\/comments?post=14874"}],"version-history":[{"count":1,"href":"https:\/\/www.ckconitsha.com\/vn\/wp-json\/wp\/v2\/posts\/14874\/revisions"}],"predecessor-version":[{"id":17833,"href":"https:\/\/www.ckconitsha.com\/vn\/wp-json\/wp\/v2\/posts\/14874\/revisions\/17833"}],"wp:attachment":[{"href":"https:\/\/www.ckconitsha.com\/vn\/wp-json\/wp\/v2\/media?parent=14874"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.ckconitsha.com\/vn\/wp-json\/wp\/v2\/categories?post=14874"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.ckconitsha.com\/vn\/wp-json\/wp\/v2\/tags?post=14874"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}