C\u00f3 nhi\u1ec1u lo\u1ea1i quy t\u1eafc t\u00ednh nhanh, ri\u00eang v\u1edbi ph\u00e9p t\u00ednh nh\u00e2n c\u00f3 th\u1ec3 k\u1ec3 ra h\u01a1n 20 lo\u1ea1i. D\u01b0\u1edbi \u0111\u00e2y l\u00e0 ba lo\u1ea1i quy t\u1eafc c\u00f3 nhi\u1ec1u \u1ee9ng d\u1ee5ng trong th\u1ef1c t\u1ebf t\u00ednh to\u00e1n. Ta chia th\u00e0nh ba tr\u01b0\u1eddng h\u1ee3p.<\/p>\n\n\n\n
Tr\u01b0\u1eddng h\u1ee3p hai s\u1ed1 nh\u00e2n h\u01a1i l\u1edbn h\u01a1n 10, 100, 1000. Ta c\u00f3 th\u1ec3 d\u00f9ng ph\u01b0\u01a1ng ph\u00e1p \u0111\u01a1n gi\u1ea3n sau \u0111\u00e2y:<\/p>\n\n\n\n
Tr\u01b0\u1edbc h\u1ebft b\u1ecf s\u1ed1 1 \u1edf m\u1ed9t th\u1eeba s\u1ed1, sau \u0111\u00f3 c\u1ed9ng v\u1edbi th\u1eeba s\u1ed1 kia;<\/p>\n\n\n\n
Th\u00eam v\u00e0o t\u1ed5ng s\u1ed1 thu \u0111\u01b0\u1ee3c c\u00e1c ch\u1eef s\u1ed1 0 (n\u1ebfu c\u00e1c th\u1eeba s\u1ed1 l\u1edbn h\u01a1n 100 th\u00ec th\u00eam v\u00e0o hai s\u1ed1; n\u1ebfu hai th\u1eeba s\u1ed1 l\u1edbn h\u01a1n 1000 th\u00eam v\u00e0o ba s\u1ed1 0 v.v\u2026);<\/p>\n\n\n\n
Sau \u0111\u00f3 l\u1eadp t\u00edch s\u1ed1 l\u00e0 t\u00edch hai ch\u1eef s\u1ed1 h\u00e0ng \u0111\u01a1n v\u1ecb;<\/p>\n\n\n\n
T\u00ednh t\u1ed5ng s\u1ed1 c\u1ee7a c\u00e1c k\u1ebft qu\u1ea3 thu \u0111\u01b0\u1ee3c t\u1eeb b\u01b0\u1edbc b v\u00e0 b\u01b0\u1edbc c; V\u00ed d\u1ee5 t\u00ednh t\u00edch s\u1ed1 108 x 103 = ?<\/p>\n\n\n\n
V\u1eady 108 x 103 = 11124<\/p>\n\n\n\n
Ta c\u00f3 th\u1ec3 gi\u1ea3i th\u00edch quy t\u1eafc t\u00ednh to\u00e1n nh\u01b0 sau \u0111\u00e2y: Hai s\u1ed1 \u0111\u00e3 cho c\u00f3 th\u1ec3 vi\u1ebft d\u01b0\u1edbi d\u1ea1ng 10a + h v\u00e0 10a + k, a, h, k l\u00e0 c\u00e1c s\u1ed1 nguy\u00ean. T\u00edch s\u1ed1 s\u1ebd l\u00e0: (10a + h) (10a + k) = 10a (10a + h + k) + hk M\u00e0 10a + h + k = (10a + h) + (10a + k) – 10a T\u00edch s\u1ed1 thu \u0111\u01b0\u1ee3c s\u1ebd c\u00f3 d\u1ea1ng: (10a + h)(10a+ k) = 10a[(10a + h) + (10a + k) – 10a] + hk<\/p>\n\n\n\n
V\u00e0 v\u00ec v\u1eady ta \u0111\u00e3 th\u1ef1c hi\u1ec7n ph\u00e9p nh\u00e2n hai s\u1ed1 nh\u01b0 \u0111\u00e3 tr\u00ecnh b\u00e0y \u1edf tr\u00ean.<\/p>\n\n\n\n
T\u00edch s\u1ed1 c\u00f3 hai th\u1eeba s\u1ed1: m\u1ed9t th\u1eeba s\u1ed1 l\u1edbn h\u01a1n 10\u2026, 100\u2026,1000\u2026 c\u00f2n m\u1ed9t th\u1eeba s\u1ed1 nh\u1ecf h\u01a1n 10\u2026,100\u2026,1000\u2026 Vi\u1ec7c t\u00ednh t\u00edch s\u1ed1 \u0111\u01b0\u1ee3c th\u1ef1c hi\u1ec7n theo c\u00e1c b\u01b0\u1edbc sau \u0111\u00e2y:<\/p>\n\n\n\n
B\u1ecf ch\u1eef s\u1ed1 1 \u1edf th\u1eeba s\u1ed1 l\u1edbn h\u01a1n 10\u2026,100\u2026,1000\u2026r\u1ed3i \u0111em k\u1ebft qu\u1ea3 c\u1ed9ng v\u00e0o th\u1eeba s\u1ed1 kia.<\/p>\n\n\n\n
Th\u00eam v\u00e0o k\u1ebft qu\u1ea3 thu \u0111\u01b0\u1ee3c c\u00e1c ch\u1eef s\u1ed1 0\u2026(v\u1edbi c\u00e1c th\u1eeba s\u1ed1 l\u1edbn h\u01a1n, nh\u1ecf h\u01a1n 100 th\u00eam 2 ch\u1eef s\u1ed1 0, v\u1edbi th\u1eeba s\u1ed1 l\u1edbn h\u01a1n, nh\u1ecf h\u01a1n 1000 th\u00eam ba ch\u1eef s\u1ed1 0\u2026v.v\u2026).<\/p>\n\n\n\n
L\u1eadp t\u00edch s\u1ed1 l\u00e0 hai ch\u1eef s\u1ed1 h\u00e0ng \u0111\u01a1n v\u1ecb c\u1ee7a s\u1ed1 l\u1edbn v\u00e0 b\u00f9 10 c\u1ee7a s\u1ed1 b\u00e9.<\/p>\n\n\n\n
Tr\u1eeb k\u1ebft qu\u1ea3 c\u00e1c b\u01b0\u1edbc c v\u00e0o k\u1ebft qu\u1ea3 c\u1ee7a b\u01b0\u1edbc b, ta s\u1ebd thu \u0111\u01b0\u1ee3c t\u00edch s\u1ed1 c\u1ea7n t\u00ednh.<\/p>\n\n\n\n
V\u00ed d\u1ee5: T\u00ednh t\u00edch s\u1ed1 1006 x 995 = ? ch\u1eef s\u1ed1 b\u00f9 tr\u00f2n c\u1ee7a s\u1ed1 b\u00e9 l\u00e0 5. d, V\u1eady 1006 x 995 = 10000970<\/p>\n\n\n\n
T\u1ed5ng qu\u00e1t h\u01a1n ta c\u00f3: (10a + h)(10a – k) = 10a (10a + h – k) – hk<\/p>\n\n\n\n
M\u00e0 10a+ h – k = (10a+ h) (10a+k) – 10a<\/p>\n\n\n\n
N\u00ean (10a + h)(10a – k) = 10a[(10a + h) + (10a – k) – 10a] – h k<\/p>\n\n\n\n
C\u1ea3 hai th\u1eeba s\u1ed1 c\u1ee7a t\u00edch s\u1ed1 \u0111\u1ec1u nh\u1ecf h\u01a1n 100, 1000, 10000 v.v\u2026<\/p>\n\n\n\n
C\u00e1ch t\u00ednh th\u1ef1c hi\u1ec7n theo c\u00e1c b\u01b0\u1edbc: a, L\u1ea5y hai th\u1eeba s\u1ed1 c\u1ed9ng v\u1edbi nhau, b\u1ecf s\u1ed1 1 \u1edf ph\u00eda b\u00ean tr\u00e1i c\u1ee7a t\u1ed5ng s\u1ed1 v\u1eeba thu \u0111\u01b0\u1ee3c. b, Th\u00eam c\u00e1c ch\u1eef s\u1ed1 0 v\u00e0o k\u1ebft qu\u1ea3 v\u1eeba thu \u0111\u01b0\u1ee3c, n\u1ebfu c\u00e1c th\u1eeba s\u1ed1 nh\u1ecf h\u01a1n 100 th\u00eam m\u1ed9t s\u1ed1 0, th\u00eam v\u00e0o hai ch\u1eef s\u1ed1 0 n\u1ebfu c\u00e1c th\u1eeba s\u1ed1 nh\u1ecf h\u01a1n 1000, th\u00eam v\u00e0o ba ch\u1eef s\u1ed1 0 n\u1ebfu c\u00e1c th\u1eeba s\u1ed1 nh\u1ecf h\u01a1n 10000 v.v\u2026 c, L\u1eadp t\u00edch l\u00e0 c\u00e1c s\u1ed1 b\u00f9 tr\u00f2n c\u1ee7a hai s\u1ed1. d, L\u1eadp t\u1ed5ng s\u1ed1 l\u00e0 k\u1ebft qu\u1ea3 c\u1ee7a b\u01b0\u1edbc b v\u00e0 b\u01b0\u1edbc c, \u0111\u00f3 ch\u00ednh l\u00e0 t\u00edch s\u1ed1 c\u1ea7n t\u00ecm.<\/p>\n\n\n\n
V\u00ed d\u1ee5: T\u00ednh t\u00edch s\u1ed1 998 x 987 = ?<\/p>\n\n\n\n
T\u1ed5ng qu\u00e1t h\u01a1n ta c\u00f3: (10a – h)(10a – k) = 10a(10a – h – k) + h k m\u00e0 10a – h – k = (10a – h) + (10a – k) – 10a. v\u00e0 (10a – h) x (10a – k) = 10a[(10a + h) + (10a – k) – 10a] + h k<\/p>\n\n\n\n
T\u1eeb kho\u00e1: T\u00ednh to\u00e1n nhanh.<\/p>\n\n\n\n
<\/p>\n\n\n\n\n\n\n","protected":false},"excerpt":{"rendered":"
C\u00f3 nhi\u1ec1u lo\u1ea1i quy t\u1eafc t\u00ednh nhanh, ri\u00eang v\u1edbi ph\u00e9p t\u00ednh nh\u00e2n c\u00f3 th\u1ec3 k\u1ec3 ra h\u01a1n 20 lo\u1ea1i. D\u01b0\u1edbi \u0111\u00e2y l\u00e0 ba lo\u1ea1i quy t\u1eafc c\u00f3 nhi\u1ec1u \u1ee9ng d\u1ee5ng trong th\u1ef1c t\u1ebf t\u00ednh to\u00e1n. Ta chia th\u00e0nh ba tr\u01b0\u1eddng h\u1ee3p. Tr\u01b0\u1eddng h\u1ee3p hai s\u1ed1 nh\u00e2n h\u01a1i l\u1edbn h\u01a1n 10, 100, 1000. Ta c\u00f3 th\u1ec3 […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":"","_disable_autopaging":false},"categories":[15,9],"tags":[],"class_list":["post-7493","post","type-post","status-publish","format-standard","hentry","category-hoi-dap-khoa-hoc","category-toan-hoc"],"_links":{"self":[{"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/posts\/7493","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/comments?post=7493"}],"version-history":[{"count":0,"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/posts\/7493\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/media?parent=7493"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/categories?post=7493"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/tags?post=7493"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}