{"id":14340,"date":"2021-03-24T10:02:43","date_gmt":"2021-03-24T03:02:43","guid":{"rendered":"https:\/\/kynaforkids.vn\/blog\/?p=14340"},"modified":"2023-07-29T08:28:41","modified_gmt":"2023-07-29T01:28:41","slug":"cau-hoi-do-vui-toan-hoc","status":"publish","type":"post","link":"https:\/\/kynaforkids.vn\/blog\/cau-hoi-do-vui-toan-hoc.html","title":{"rendered":"[TOP 25+] C\u00e2u h\u1ecfi \u0111\u1ed1 vui to\u00e1n h\u1ecdc gi\u00fap tr\u1ebb s\u00e1ng t\u1ea1o"},"content":{"rendered":"

Top 25+ c\u00e2u h\u1ecfi \u0111\u1ed1 vui to\u00e1n h\u1ecdc d\u00e0nh cho b\u00e9 m\u00e0 Kynaforkids.vn b\u1eadt m\u00ed d\u01b0\u1edbi \u0111\u00e2y s\u1ebd gi\u00fap b\u00e9 nh\u00e0 b\u1ea1n v\u1eeba \u0111\u01b0\u1ee3c gi\u1ea3i tr\u00ed v\u1eeba n\u00e2ng cao kh\u1ea3 n\u0103ng to\u00e1n h\u1ecdc c\u1ee7a m\u00ecnh.<\/p>\n

25 C\u00e2u h\u1ecfi \u0111\u1ed1 vui to\u00e1n h\u1ecdc d\u00e0nh cho b\u00e9<\/h2>\n

C\u00e2u h\u1ecfi 1: <\/strong>B\u00e9 h\u00e3y nh\u00ecn h\u00ecnh v\u00e0 cho bi\u1ebft \u0111\u00e1p \u00e1n<\/p>\n

\"C\u00e2u<\/p>\n

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-> \u0110\u00e1p \u00e1n:<\/strong> Con s\u00f3c = 4; con ch\u00f3 = 9; m\u00e8o = 8; b\u1ec3 c\u00e1 = 11; \u0111i\u1ec1n v\u00e0o d\u1ea5u h\u1ecfi ch\u1ea5m l\u00e0 = 176.<\/p>\n

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C\u00e2u h\u1ecfi 2<\/strong>: B\u00e9 h\u00e3y nh\u00ecn h\u00ecnh v\u00e0 cho bi\u1ebft \u0111\u00e1p \u00e1n<\/p>\n

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\"C\u00e2u<\/p>\n

-> \u0110\u00e1p \u00e1n:<\/strong> Tr\u1ea3 l\u1eddi ch\u00ednh x\u00e1c l\u00e0: Con ch\u00f3 \u0111\u1ea5t = 12, m\u1eb7t tr\u1eddi = 0, m\u0169 = 6, \u0111i\u1ec1n v\u00e0o d\u1ea5u h\u1ecfi ch\u1ea5m l\u00e0 = 6.<\/p>\n

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C\u00e2u h\u1ecfi h\u1ecfi 3<\/strong>: B\u00e9 h\u00e3y nh\u00ecn h\u00ecnh v\u00e0 cho bi\u1ebft \u0111\u00e1p \u00e1n<\/p>\n

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\"C\u00e2u<\/p>\n

-> \u0110\u00e1p \u00e1n:<\/strong> \u0110\u00e1m m\u00e2y = 7, b\u00f4ng tuy\u1ebft = 20, \u0111i\u1ec1n v\u00e0o d\u1ea5u h\u1ecfi ch\u1ea5m l\u00e0 = 33 (ch\u00fa ch\u00f3 \u0111\u1ea5t v\u00e0 chi\u1ebfc m\u0169 c\u00f3 th\u1ec3 l\u00e0 hai s\u1ed1 b\u1ea5t k\u1ef3 v\u1edbi t\u1ed5ng b\u1eb1ng 13).<\/p>\n

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C\u00e2u h\u1ecfi 4<\/strong>: B\u00e9 h\u00e3y nh\u00ecn h\u00ecnh v\u00e0 cho bi\u1ebft \u0111\u00e1p \u00e1n<\/p>\n

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\"C\u00e2u<\/p>\n

-> \u0110\u00e1p \u00e1n:<\/strong> Con s\u00f3c = 4; con ch\u00f3 = 4; b\u1ec3 c\u00e1 = 23; con m\u00e8o = 22; \u0111i\u1ec1n v\u00e0o d\u1ea5u h\u1ecfi ch\u1ea5m l\u00e0 = 111.<\/p>\n

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C\u00e2u h\u1ecfi 5<\/strong>: B\u00e9 h\u00e3y nh\u00ecn h\u00ecnh v\u00e0 cho bi\u1ebft \u0111\u00e1p \u00e1n<\/p>\n

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\"C\u00e2u<\/p>\n

-> \u0110\u00e1p \u00e1n:<\/strong> C\u00e2y k\u1eb9o =12; ng\u00f4i nh\u00e0 = 36; b\u00e1nh h\u00ecnh ng\u01b0\u1eddi = 6; b\u00e1nh m\u00e0u \u0111\u1ecf = 12; \u0111i\u1ec1n v\u00e0o d\u1ea5u h\u1ecfi ch\u1ea5m l\u00e0 = 66.<\/p>\n

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C\u00e2u h\u1ecfi 6<\/strong>: Matt l\u00e0 ng\u01b0\u1eddi ch\u1ea1y nhanh th\u1ee9 50 v\u00e0 c\u0169ng l\u00e0 ng\u01b0\u1eddi ch\u1ea1y ch\u1eadm th\u1ee9 50 trong cu\u1ed9c thi \u1edf tr\u01b0\u1eddng. Gi\u1ea3 s\u1eed kh\u00f4ng c\u00f3 hai ng\u01b0\u1eddi n\u00e0o ch\u1ea1y c\u00f9ng t\u1ed1c \u0111\u1ed9, t\u1ed5ng c\u1ed9ng c\u00f3 bao nhi\u00eau h\u1ecdc sinh \u1edf tr\u01b0\u1eddng Matt tham gia ch\u1ea1y?<\/p>\n

-> \u0110\u00e1p \u00e1n:<\/strong> Tr\u01b0\u1eddng Matt c\u00f3 99 h\u1ecdc sinh tham gia ch\u1ea1y. (N\u1ebfu Matt ch\u1ea1y nhanh th\u1ee9 50, c\u1eadu s\u1ebd t\u01b0\u01a1ng \u1ee9ng v\u1edbi s\u1ed1 50 trong d\u00e3y 1, 2, 3… 50. \u0110\u1ec3 l\u00e0 ng\u01b0\u1eddi ch\u1ea1y ch\u1eadm th\u1ee9 50, c\u1eadu ph\u1ea3i l\u00e0 s\u1ed1 50 trong d\u00e3y 50, 51, 52… 99, b\u1edfi t\u1eeb 50 \u0111\u1ebfn 99 c\u00f3 50 s\u1ed1 t\u1ed5ng c\u1ed9ng).<\/p>\n

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C\u00e2u h\u1ecfi 7<\/strong>: N\u1ebfu 5 con m\u00e8o c\u00f3 th\u1ec3 b\u1eaft 5 con chu\u1ed9t trong 5 ph\u00fat, c\u1ea7n c\u00f3 bao nhi\u00eau con m\u00e8o \u0111\u1ec3 b\u1eaft \u0111\u01b0\u1ee3c 100 con chu\u1ed9t trong 100 ph\u00fat?<\/p>\n

-> \u0110\u00e1p \u00e1n:<\/strong> 5 con m\u00e8o (5 con m\u00e8o s\u1ebd ti\u1ebfp t\u1ee5c b\u1eaft 5 con chu\u1ed9t 5 ph\u00fat m\u1ed9t l\u1ea7n, su\u1ed1t 100 ph\u00fat).<\/p>\n

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C\u00e2u h\u1ecfi 8<\/strong>: Thi\u1ec7n \u0111\u01b0\u1ee3c ngh\u1ec9 h\u1ecdc, \u1edf nh\u00e0 r\u1ee7 V\u0169 gi\u1ea3i c\u00e1c b\u00e0i to\u00e1n x\u1ebfp h\u00ecnh b\u1eb1ng que di\u00eam. Sau v\u00e0i c\u00e2u kh\u00e1 d\u1ec5, Thi\u1ec7n ch\u1ec9 m\u1ed9t c\u00e2u m\u1edbi cho V\u0169:<\/p>\n

– Em xem, c\u00e2u n\u00e0y c\u0169ng th\u00fa v\u1ecb \u0111\u1ea5y ch\u1ee9.<\/p>\n

V\u0169 gh\u00e9 m\u1eaft v\u00e0o nh\u00ecn r\u1ed3i \u0111\u1ecdc to:<\/p>\n

– H\u00e3y d\u00f9ng 3 que di\u00eam \u0111\u1ec3 x\u1ebfp th\u00e0nh m\u1ed9t s\u1ed1 l\u1edbn h\u01a1n 3 nh\u01b0ng nh\u1ecf h\u01a1n 4.<\/p>\n

V\u0169 loay hoay m\u1ed9t l\u00fac v\u1eabn ch\u01b0a t\u00ecm ra, \u0111\u00e0nh nh\u1edd anh gi\u1ea3i gi\u00fap. V\u1eady Thi\u1ec7n \u0111\u00e3 l\u00e0m th\u1ebf n\u00e0o nh\u1ec9?<\/p>\n

-> \u0110\u00e1p \u00e1n:<\/strong> B\u1ea1n d\u00f9ng 3 que \u0111\u1ec3 x\u1ebfp th\u00e0nh s\u1ed1 pi (3 < 3.14 < 4).<\/p>\n

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C\u00e2u h\u1ecfi 9<\/strong>: Vi\u00ean t\u01b0\u1edbng n\u1ecd mu\u1ed1n ch\u1ecdn m\u1ed9t ng\u01b0\u1eddi l\u00ednh th\u00f4ng minh nh\u1ea5t \u0111\u1ec3 \u0111\u1ec1 b\u1ea1t l\u00e0m s\u0129 quan ch\u1ec9 huy. \u00d4ng t\u1eadp trung m\u1ecdi ng\u01b0\u1eddi trong s\u00e2n t\u1eadp r\u1ed3i n\u00f3i:<\/p>\n

– Ai c\u00f3 c\u00e1ch g\u00ec \u0111\u1ec3 l\u00ednh g\u00e1c cho ra kh\u1ecfi s\u00e2n \u0111\u01b0\u1eddng ho\u00e0ng, vui v\u1ebb, s\u1ebd \u0111\u01b0\u1ee3c th\u0103ng ch\u1ee9c.<\/p>\n

M\u1ecdi ng\u01b0\u1eddi \u0111ang v\u1eaft \u00f3c ra suy ngh\u0129 m\u00e0 v\u1eabn ch\u01b0a t\u00ecm ra c\u00e1ch n\u00e0o. L\u00fac n\u00e0y, m\u1ed9t anh l\u00ednh \u0111\u1ebfn g\u1ea7n l\u00ednh g\u00e1c n\u00f3i duy nh\u1ea5t m\u1ed9t c\u00e2u. Th\u1ebf l\u00e0 l\u00ednh g\u00e1c li\u1ec1n cho anh ta ra ngo\u00e0i.<\/p>\n

B\u1ea1n th\u1eed \u0111o\u00e1n xem anh l\u00ednh \u0111\u00e3 n\u00f3i g\u00ec v\u1edbi ng\u01b0\u1eddi l\u00ednh g\u00e1c \u0111\u1ec3 \u0111\u01b0\u1ee3c ra ngo\u00e0i?<\/p>\n

-> \u0110\u00e1p \u00e1n:<\/strong> \u0110\u00f3 l\u00e0 c\u00e2u: “Th\u00f4i, m\u00ecnh ch\u1ea3 tham gia n\u1eefa”. Th\u1ebf l\u00e0 nghi\u1ec5m nhi\u00ean anh ta \u0111\u01b0\u1ee3c ra ngo\u00e0i.<\/p>\n

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C\u00e2u h\u1ecfi 10<\/strong>: Lan \u0111\u1ebfn nh\u00e0 Thanh ch\u01a1i g\u1eb7p l\u00fac m\u1eb9 Thanh \u0111ang chu\u1ea9n b\u1ecb l\u00e0m c\u1ed7 c\u00fang r\u1eb1m. Bi\u1ebft m\u1eb9 Thanh n\u1ea5u \u0103n r\u1ea5t gi\u1ecfi, n\u00ean Lan t\u00f2 m\u00f2 xu\u1ed1ng b\u1ebfp xem.<\/p>\n

Lan th\u1ea5y b\u00e1c b\u00e0y bi\u1ec7n bao nhi\u00eau l\u00e0 rau qu\u1ea3, th\u1ecbt c\u00e1… tr\u00ean b\u00e0n, \u0111\u1ec3 chu\u1ea9n n\u1ea5u n\u01b0\u1edbng.<\/p>\n

Lan ch\u1ee3t ch\u00fa \u00fd t\u1edbi 5 chi\u1ebfc b\u00e1t th\u1ee7y tinh \u0111\u1ef1ng n\u01b0\u1edbc \u0111\u1ec3 tr\u00ean c\u00e1i b\u00e0n nh\u1ecf.<\/p>\n

Th\u1ea5y Lan t\u1ecf r\u00f5 s\u1ef1 t\u00f2 m\u00f2, m\u1eb9 Thanh m\u1ec9m c\u01b0\u1eddi:<\/p>\n

– \u0110\u00e2y l\u00e0 5 b\u00e1t gia v\u1ecb: r\u01b0\u1ee3u tr\u1eafng, n\u01b0\u1edbc mu\u1ed1i, d\u1ea5m, n\u01b0\u1edbc \u0111\u01b0\u1eddng, n\u01b0\u1edbc s\u00f4i. Ch\u00fang \u0111\u1ec1u trong su\u1ed1t, kh\u00f4ng m\u00e0u v\u00e0 c\u00f3 th\u1ec3 u\u1ed1ng \u0111\u01b0\u1ee3c. M\u1ed7i b\u00e1t n\u00e0y, ch\u00e1u ch\u1ec9 \u0111\u01b0\u1ee3c th\u1eed m\u1ed9t l\u1ea7n duy nh\u1ea5t, th\u00ec li\u1ec7u ch\u00e1u c\u00f3 ph\u00e2n bi\u1ec7t \u0111\u01b0\u1ee3c b\u00e1t n\u00e0o \u0111\u1ef1ng g\u00ec \u0111\u01b0\u1ee3c kh\u00f4ng?<\/p>\n

Lan l\u00fang t\u00fang qu\u00e1, v\u00ec c\u00f4 b\u00e9 \u0111\u00e3 bao gi\u1edd ph\u1ea3i v\u00e0o b\u1ebfp \u0111\u00e2u. B\u1ea1n h\u00e3y gi\u00fap Lan v\u1edbi nh\u00e9!<\/p>\n

-> \u0110\u00e1p \u00e1n:<\/strong> N\u00f3i l\u00e0 “th\u1eed” th\u00f4i, ch\u1ee9 c\u1ea7n ph\u1ea3i bi\u1ebft c\u00f3 nh\u1eefng c\u00e1ch kh\u00e1c nhau, v\u00ec ta c\u00f3 5 gi\u00e1c quan c\u01a1 m\u00e0.<\/p>\n

– \u0110\u1ea7u ti\u00ean, s\u1edd tay t\u00ecm ra ngay b\u00e1t n\u01b0\u1edbc s\u00f4i.<\/p>\n

– M\u0169i ng\u1eedi s\u1ebd gi\u00fap ph\u00e1t hi\u1ec7n ra d\u1ea5m v\u00e0 r\u01b0\u1ee3u.<\/p>\n

– C\u00f2n l\u1ea1i hai b\u00e1t, th\u00ec… n\u1ebfm n\u01b0\u1edbc trong m\u1ed9t b\u00e1t l\u00e0 bi\u1ebft ngay b\u00e1t n\u00e0o \u0111\u1ef1ng n\u01b0\u1edbc mu\u1ed1i, b\u00e1t n\u00e0o \u0111\u1ef1ng n\u01b0\u1edbc \u0111\u01b0\u1eddng.<\/p>\n

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C\u00e2u h\u1ecfi 11<\/strong>: D\u00ec \u0111em b\u00e9 B\u1ea1ch \u0111\u1ebfn ch\u01a1i nh\u00e0 V\u0169, c\u00f4 b\u00e9 ch\u01b0a \u0111\u1ea7y 10 th\u00e1ng tu\u1ed5i. M\u1eb9 b\u1ebf b\u00e9 B\u1ea1ch khen:<\/p>\n

– B\u00e9 B\u1ea1ch nh\u00e0 m\u00ecnh l\u1edbn nhanh th\u1eadt, b\u00e2y gi\u1edd ch\u1eafc ph\u1ea3i 9 c\u00e2n r\u1ed3i.<\/p>\n

– D\u00ec \u01a1i, b\u00e9 B\u1ea1ch b\u00e9o th\u1ebf c\u01a1 \u00e0? \u2013 V\u0169 tr\u00f2n m\u1eaft ng\u1ea1c nhi\u00ean, v\u00ec l\u00fac m\u1edbi sinh b\u00e9 B\u1ea1ch v\u1eeba b\u00e9 l\u1ea1i v\u1eeba g\u1ea7y, l\u00e0m c\u1ea3 nh\u00e0 r\u1ea5t lo.<\/p>\n

V\u0169 nhanh nh\u1eb9n l\u1ea5y c\u00e2n ra.<\/p>\n

– B\u00e9 B\u1ea1ch, ngoan n\u00e0o, ng\u1ed3i l\u00ean \u0111\u00e2y.<\/p>\n

V\u0169 mang c\u00e2n ra \u0111\u1ecbnh c\u00e2n b\u00e9 B\u1ea1ch nh\u01b0ng ch\u1eb3ng d\u1ec5 ch\u00fat n\u00e0o. B\u00e9 r\u1ea5t ngh\u1ecbch, to\u00e0n b\u00f2 xu\u1ed1ng. D\u00ec c\u01b0\u1eddi n\u00f3i:<\/p>\n

– V\u0169 \u00e0, th\u1ebf kh\u00f4ng c\u00e2n em \u0111\u01b0\u1ee3c \u0111\u00e2u.<\/p>\n

– V\u1eady d\u00ec c\u00f3 c\u00e1ch n\u00e0o kh\u00f4ng?<\/p>\n

– \u0110\u01b0\u01a1ng nhi\u00ean r\u1ed3i, ch\u00e1u th\u1eed ngh\u0129 xem.<\/p>\n

V\u0169 ng\u1ed3i im suy ngh\u0129.<\/p>\n

\u0110\u1ed1 b\u1ea1n V\u0169 s\u1ebd l\u00e0m th\u1ebf n\u00e0o \u0111\u1ec3 bi\u1ebft \u0111\u01b0\u1ee3c tr\u1ecdng l\u01b0\u1ee3ng c\u1ee7a b\u00e9 B\u1ea1ch nh\u1ec9?<\/p>\n

-> \u0110\u00e1p \u00e1n:<\/strong> \u0110\u1ea7u ti\u00ean cho V\u0169 c\u00e2n tr\u01b0\u1edbc, cho V\u0169 b\u1ebf b\u00e9 B\u1ea1ch c\u00e2n l\u1ea7n hai. Sau \u0111\u00f3 tr\u1eeb \u0111i tr\u1ecdng l\u01b0\u1ee3ng c\u1ee7a V\u0169 l\u00e0 ra s\u1ed1 c\u00e2n c\u1ee7a b\u00e9 B\u1ea1ch.<\/p>\n

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C\u00e2u h\u1ecfi 12<\/strong>: S\u00f3i v\u00e0 C\u1eebu c\u00f9ng u\u1ed1ng n\u01b0\u1edbc \u1edf m\u1ed9t kh\u00fac s\u00f4ng. S\u00f3i r\u1ea5t mu\u1ed1n \u0103n th\u1ecbt C\u1eebu, n\u00ean c\u1ed1 n\u1eb7n ra m\u1ed9t c\u00e1i c\u1edb. N\u00f3 l\u1ea1i g\u1ea7n C\u1eebu, cao gi\u1ecdng n\u00f3i<\/p>\n

– Nghe r\u00f5 \u0111\u00e2y, ta s\u1ebd \u0111\u1eb7t cho ng\u01b0\u01a1i 50 c\u00e2u h\u1ecfi. Ng\u01b0\u01a1i ch\u1ec9 \u0111\u01b0\u1ee3c tr\u1ea3 l\u1eddi t\u1ea5t c\u1ea3 b\u1eb1ng m\u1ed9t c\u00e2u, n\u1ebfu kh\u00f4ng ta s\u1ebd \u0103n th\u1ecbt ng\u01b0\u01a1i.<\/p>\n

C\u1eebu s\u1ee3 run c\u1ea7m c\u1eadp, \u0111\u00e0nh \u0111\u1ed3ng \u00fd.<\/p>\n

S\u00f3i n\u00f3i li\u1ec1n m\u1ed9t m\u1ea1ch 50 c\u00e2u h\u1ecfi v\u1ec1 m\u1ecdi v\u1ea5n \u0111\u1ec1. N\u00f3 ch\u1eafc m\u1ea9m phen n\u00e0y s\u1ebd \u0103n th\u1ecbt \u0111\u01b0\u1ee3c C\u1eebu. Ai d\u00e8, C\u1eebu ch\u1ec9 n\u00f3i m\u1ed9t c\u00e2u l\u00e0 \u0111\u00e3 tr\u1ea3 l\u1eddi \u0111\u01b0\u1ee3c c\u1ea3 50 c\u00e2u h\u1ecfi c\u1ee7a S\u00f3i.<\/p>\n

B\u1ea1n th\u1eed \u0111o\u00e1n xem \u0111\u00f3 l\u00e0 c\u00e2u g\u00ec v\u1eady?<\/p>\n

-> \u0110\u00e1p \u00e1n:<\/strong> Trong l\u00fac lo s\u1ee3 t\u1ed9t c\u00f9ng. C\u1eebu ch\u1ee3t ngh\u0129 ra c\u00e1ch \u0111\u1ed1i ph\u00f3 th\u00f4ng minh \u0111\u1ec3 tho\u00e1t kh\u1ecfi nanh vu\u1ed1t S\u00f3i. C\u1eebu \u0111\u00e1p r\u1eb1ng:<\/p>\n

– T\u00f4i kh\u00f4ng bi\u1ebft!<\/p>\n

S\u00f3i \u0111\u00e0nh c\u1ee9ng h\u1ecdng b\u1ecf \u0111i d\u00f9 th\u00e8m r\u00f5 d\u00e3i, song v\u1eabn kh\u00f4ng \u0111\u1ee5ng \u0111\u01b0\u1ee3c \u0111\u1ebfn C\u1eebu.<\/p>\n

 <\/p>\n

C\u00e2u h\u1ecfi 13<\/strong>: N\u01b0\u1edbc M\u1ef9 l\u00e0 thi\u00ean \u0111\u01b0\u1eddng c\u1ee7a nh\u1eefng ng\u01b0\u1eddi d\u00e1m m\u01a1 \u01b0\u1edbc. Bao nhi\u00eau tri\u1ec7u ph\u00fa \u0111\u00e3 \u0111i l\u00ean t\u1eeb hai b\u00e0n tay tr\u1eafng. Ch\u1ec9 c\u1ea7n b\u1ea1n ch\u1ecbu kh\u00f3 t\u00ecm t\u00f2i suy ngh\u0129, d\u00e1m l\u00e0m d\u00e1m ch\u1ecbu th\u00ec kh\u00f4ng c\u00f3 g\u00ec l\u00e0 kh\u00f4ng th\u1ec3 l\u00e0m \u0111\u01b0\u1ee3c.<\/p>\n

Nh\u00e0 t\u01b0 b\u1ea3n n\u1ecd r\u1ea5t gi\u00e0u v\u00e0 c\u0169ng r\u1ea5t gi\u1ecfi l\u00e0m \u0103n. \u00d4ng ta \u0111\u1ea7u t\u01b0 m\u1ed9t ph\u1ea7n v\u00e0o \u0111\u1ecba \u1ed1c, v\u00e0 c\u1ee9 m\u1ed7i th\u00e1ng s\u1ed1 ti\u1ec1n \u1ea5y l\u1ea1i sinh l\u00e3i g\u1ea5p \u0111\u00f4i. Sau m\u1ed9t n\u0103m \u2013 12 th\u00e1ng, s\u1ed1 ti\u1ec1n \u0111\u00e3 l\u00ean t\u1edbi 100 tri\u1ec7u \u0111\u00f4la. V\u1eady b\u1ea1n xem v\u00e0o l\u00fac n\u00e0o th\u00ec \u00f4ng ta c\u00f3 s\u1ed1 ti\u1ec1n l\u00e0 50 tri\u1ec7u?<\/p>\n

-> \u0110\u00e1p \u00e1n:<\/strong> T\u1edbi th\u00e1ng 12 th\u00ec \u00f4ng ta c\u00f3 100 tri\u1ec7u \u0111\u00f4la. C\u1ee9 sau m\u1ed7i th\u00e1ng s\u1ed1 ti\u1ec1n l\u1ea1i sinh l\u00e3i g\u1ea5p \u0111\u00f4i, n\u00ean t\u1edbi th\u00e1ng 11 \u00f4ng ta c\u00f3 s\u1ed1 ti\u1ec1n v\u1eeba b\u1eb1ng m\u1ed9t n\u1eeda s\u1ed1 ti\u1ec1n thu \u0111\u01b0\u1ee3c v\u00e0o th\u00e1ng th\u1ee9 12, t\u1ee9c l\u00e0 50 tri\u1ec7u \u0111\u00f4la.<\/p>\n

 <\/p>\n

C\u00e2u h\u1ecfi 14<\/strong>: M\u1ed9t ch\u00e0ng thanh ni\u00ean qu\u00fd t\u1ed9c v\u00e0o c\u1eeda h\u00e0ng b\u00e1nh, y\u00eau c\u1ea7u:<\/p>\n

– H\u00e3y chu\u1ea9n b\u1ecb cho ta 9 c\u00e1i b\u00e1nh, \u0111\u1ef1ng v\u00e0o 4 c\u00e1i h\u1ed9p b\u00e1nh, m\u00e0 m\u1ed7i h\u1ed9p ch\u1ec9 c\u00f3 \u0111\u00fang 3 c\u00e1i b\u00e1nh!<\/p>\n

\u00d4ng ch\u1ee7 \u0111ang ng\u01a1 ng\u00e1c th\u00ec ch\u00fa b\u00e9 Gauss \u2013 ng\u01b0\u1eddi sau n\u00e0y tr\u1edf th\u00e0nh nh\u00e0 to\u00e1n h\u1ecdc n\u1ed5i ti\u1ebfng ng\u01b0\u1eddi \u0110\u1ee9c \u2013 ch\u1ea1y ra \u0111\u1ee1 l\u1eddi \u00f4ng ch\u1ee7:<\/p>\n

– Xin ng\u00e0i c\u1ee9 y\u00ean t\u00e2m, b\u00e1nh s\u1ebd \u0111\u01b0\u1ee3c x\u1ebfp theo \u0111\u00fang y\u00eau c\u1ea7u ngay \u0111\u00e2y \u1ea1.<\/p>\n

V\u1eady Gauss \u0111\u00e3 l\u00e0m th\u1ebf n\u00e0o?<\/p>\n

-> \u0110\u00e1p \u00e1n:<\/strong> C\u1eadu b\u00e9 Gauss x\u1ebfp 9 c\u00e1i b\u00e1nh v\u00e0o 3 h\u1ed9p b\u00e1nh nh\u1ecf. Xong \u0111\u1eb7t 3 h\u1ed9p b\u00e1nh \u0111\u00f3 v\u00e0o m\u1ed9t c\u00e1i h\u1ed9p to.<\/p>\n

 <\/p>\n

C\u00e2u h\u1ecfi 15<\/strong>: B\u1ed1 Nam n\u0103m nay 45 tu\u1ed5i, Nam 15 tu\u1ed5i. Suy ra b\u1ed1 Nam g\u1ea5p 3 l\u1ea7n tu\u1ed5i Nam.<\/p>\n

Nh\u01b0ng h\u00f4m tr\u01b0\u1edbc Thanh l\u1ea1i \u0111\u1ed1 Nam:<\/p>\n

– \u0110\u1ed1 c\u1eadu t\u00ecm th\u1ea5y m\u1ed9t tr\u01b0\u1eddng h\u1ee3p m\u00e0 \u1edf c\u00f9ng nh\u00e0, ng\u01b0\u1eddi n\u1ecd l\u1ea1i g\u1ea5p 720 l\u1ea7n tu\u1ed5i ng\u01b0\u1eddi kia.<\/p>\n

-> \u0110\u00e1p \u00e1n:<\/strong> B\u1ed1 Nam g\u1ea5p 3 l\u1ea7n tu\u1ed5i Nam l\u00e0 t\u00ednh theo n\u0103m. \u0110\u00f3 g\u1ecdi l\u00e0 n\u0103m tu\u1ed5i. Song, trong th\u1ef1c t\u1ebf, kh\u00f4ng ch\u1ec9 c\u00f3 n\u0103m tu\u1ed5i. \u1ede tr\u01b0\u1eddng h\u1ee3p sau, ch\u1ec9 c\u00f2n c\u00e1ch t\u00ednh s\u1ef1 ch\u00eanh l\u1ec7ch tu\u1ed5i theo th\u00e1ng. \u0110\u00f3 l\u00e0 th\u00e1ng tu\u1ed5i. \u00d4ng 60 tu\u1ed5i, ch\u00e1u m\u1edbi sinh ra \u0111\u01b0\u1ee3c tr\u00f2n 1 th\u00e1ng. V\u00ec 60 n\u0103m = 720 th\u00e1ng, do v\u1eady \u00f4ng g\u1ea5p 720 l\u1ea7n tu\u1ed5i ch\u00e1u.<\/p>\n

 <\/p>\n

C\u00e2u h\u1ecfi 16<\/strong>: B\u00e9 Minh n\u0103m nay v\u00e0o l\u1edbp m\u1ed9t. M\u1eb9 \u0111\u00e3 d\u1ea1y b\u00e9 bi\u1ebft \u0111\u1ecdc, bi\u1ebft vi\u1ebft t\u1ea5t c\u1ea3 c\u00e1c ch\u1eef c\u00e1i. V\u00e0 m\u1eb9 c\u00f2n mua cho b\u00e9 m\u1ed9t chi\u1ebfc b\u1ea3ng t\u1ef1 x\u00f3a \u0111\u1ec3 b\u00e9 h\u1ecdc v\u1ebd, v\u00e0 m\u1ed9t b\u1ed9 \u0111\u1ed3 ch\u01a1i x\u1ebfp ch\u1eef kh\u00e1 \u0111\u1eb9p.<\/p>\n

Ch\u1ec9 c\u00f2n thi\u1ebfu m\u1ed9t c\u00e1i c\u1eb7p v\u00e0 b\u1ed9 qu\u1ea7n \u00e1o \u0111\u1ed3ng ph\u1ee5c n\u1eefa th\u00f4i l\u00e0 b\u00e9 s\u1ebd ra d\u00e1ng m\u1ed9t c\u00f4 “sinh vi\u00ean” nh\u1ecf. M\u1eb9 h\u1ee9a mai s\u1ebd d\u1eabn b\u00e9 \u0111i si\u00eau th\u1ecb mua c\u1eb7p v\u00e0 qu\u1ea7n \u00e1o n\u00ean ph\u1ea3i d\u1eady s\u1edbm.<\/p>\n

B\u00e9 v\u1eb7n \u0111\u1ed3ng h\u1ed3 b\u00e1o th\u1ee9c \u0111\u00fang 8h v\u00e0 \u0111\u1ed3ng h\u1ed3 c\u0169ng k\u00eau r\u1ea5t \u0111\u00fang gi\u1edd. Nh\u01b0ng m\u1eb9 l\u1ea1i b\u1ea3o nh\u01b0 v\u1eady l\u00e0 kh\u00f4ng \u0111\u01b0\u1ee3c, v\u00ec b\u00e9 th\u01b0\u1eddng \u0111i ng\u1ee7 v\u00e0o l\u00fac 7h. Theo b\u1ea1n, t\u1ea1i sao m\u1eb9 b\u00e9 Minh l\u1ea1i b\u1ea3o nh\u01b0 v\u1eady?<\/p>\n

-> \u0110\u00e1p \u00e1n:<\/strong> B\u00e9 \u0111i ng\u1ee7 l\u00fac 7h, 8h t\u1ed1i \u0111\u1ed3ng h\u1ed3 \u0111\u00e3 k\u00eau n\u00ean b\u00e9 m\u1edbi ng\u1ee7 \u0111\u01b0\u1ee3c c\u00f3 1 ti\u1ebfng \u0111\u1ed3ng h\u1ed3.<\/p>\n

 <\/p>\n

C\u00e2u h\u1ecfi 17<\/strong>: Tr\u1ea1m thu\u1ebf c\u1ee7a t\u00ean c\u01b0\u1edbp kh\u00e9t ti\u1ebfng quy \u0111\u1ecbnh nh\u01b0 sau:<\/p>\n

– N\u1ebfu ai \u0111em gia s\u00fac qua tr\u1ea1m thu\u1ebf \u0111\u1ec1u b\u1ecb thu m\u1ed9t n\u1eeda. N\u1ebfu s\u1ed1 gia s\u00fac l\u1ebb s\u1ebd kh\u1ea5u th\u00eam n\u1eeda con. Sau \u0111\u00f3 s\u1ebd tr\u1ea3 l\u1ea1i cho ch\u1ee7 1 con.<\/p>\n

Ba anh em n\u1ecd d\u1eaft 5 con d\u00ea qua tr\u1ea1m. Th\u1ea5y quy \u0111\u1ecbnh \u0111\u00f3, ng\u01b0\u1eddi anh c\u1ea3 li\u1ec1n ngh\u0129 ra m\u1ed9t k\u1ebf. H\u1ecd qua tr\u1ea1m r\u1ea5t d\u1ec5 d\u00e0ng, kh\u00f4ng m\u1ea5t m\u1ed9t con d\u00ea n\u00e0o.<\/p>\n

B\u1ea1n c\u00f3 bi\u1ebft h\u1ecd \u0111\u00e3 l\u00e0m th\u1ebf n\u00e0o kh\u00f4ng?<\/p>\n

-> \u0110\u00e1p \u00e1n:<\/strong> H\u1ecd chia nhau m\u1ed7i ng\u01b0\u1eddi ch\u1ec9 mang 1 ho\u1eb7c 2 con d\u00ea. Nh\u01b0 v\u1eady s\u1ebd kh\u00f4ng m\u1ed9t con d\u00ea n\u00e0o c\u1ea3.<\/p>\n

 <\/p>\n

C\u00e2u h\u1ecfi 18<\/strong>: Tr\u00ean \u0111\u1ed3ng c\u1ecf c\u00f3 6 con b\u00f2, \u0111\u1ebfm \u0111i \u0111\u1ebfm l\u1ea1i ch\u1ec9 c\u00f3 12 c\u00e1i ch\u00e2n. T\u1ea1i sao?<\/p>\n

-> \u0110\u00e1p \u00e1n: <\/strong>Con b\u00f2 n\u00e0y c\u01b0\u1ee1i l\u00ean l\u01b0ng con b\u00f2 kia theo d\u00e2y chuy\u1ec1n v\u00e0 v\u00f2ng tr\u00f2n n\u00ean m\u1ed7i con ch\u1ec9 c\u00f3 2 ch\u00e2n!<\/p>\n

 <\/p>\n

C\u00e2u h\u1ecfi 19<\/strong>: 2 con v\u1ecbt \u0111i tr\u01b0\u1edbc 2 con v\u1ecbt, 2 con v\u1ecbt \u0111i sau 2 con v\u1ecbt, 2 con v\u1ecbt \u0111i gi\u1eefa 2 con v\u1ecbt. H\u1ecfi c\u00f3 m\u1ea5y con v\u1ecbt?<\/p>\n

-> \u0110\u00e1p \u00e1n: <\/strong>4<\/p>\n

 <\/p>\n

C\u00e2u h\u1ecfi 20<\/strong>: Ba\u0301c Toa\u0300n c\u00e2\u0300n 8 phu\u0301t \u0111\u00ea\u0309 c\u01b0a m\u00f4\u0323t khu\u0301c g\u00f4\u0303 tha\u0300nh 3 \u0111oa\u0323n co\u0301 chi\u00ea\u0300u b\u0103\u0300ng nhau. Ho\u0309i ba\u0301c Toa\u0300n pha\u0309i m\u00e2\u0301t bao nhi\u00eau phu\u0301t \u0111\u00ea\u0309 c\u01b0a khu\u0301c g\u00f4\u0303 \u0111o\u0301 tha\u0300nh 9 \u0111oa\u0323n b\u0103\u0300ng nhau?<\/p>\n

-> \u0110\u00e1p \u00e1n:<\/strong> 32 ph\u00fat<\/p>\n

 <\/p>\n

C\u00e2u h\u1ecfi 21<\/strong>: Trong h\u00f4\u0323p co\u0301 25 vi\u00ean bi Xanh, 18 vi\u00ean bi \u0110o\u0309 va\u0300 13 vi\u00ean bi Va\u0300ng. Kh\u00f4ng nhi\u0300n va\u0300o h\u00f4\u0323p, c\u00e2\u0300n l\u00e2\u0301y ra i\u0301t nh\u00e2\u0301t bao nhi\u00eau vi\u00ean bi \u0111\u00ea\u0309 ch\u0103\u0301c ch\u0103\u0301n r\u0103\u0300ng trong s\u00f4\u0301 bi l\u00e2\u0301y ra co\u0301 i\u0301t nh\u00e2\u0301t 10 vi\u00ean Xanh, 9 vi\u00ean \u0110o\u0309 va\u0300 8 vi\u00ean Va\u0300ng?<\/p>\n

-> \u0110\u00e1p \u00e1n:<\/strong> C\u1ea7n l\u1ea5y \u00edt nh\u1ea5t s\u1ed1 vi\u00ean bi l\u00e0: 25 + 18 + 8 = 51 (vi\u00ean bi)<\/p>\n

 <\/p>\n

C\u00e2u h\u1ecfi 22<\/strong>: T\u00ecm m\u1ed9t s\u1ed1 c\u00f3 8 ch\u1eef s\u1ed1 s\u1eed d\u1ee5ng c\u00e1c ch\u1eef s\u1ed1 1, 2, 3, 4 m\u1ed7i ch\u1eef s\u1ed1 ch\u1ec9 s\u1eed d\u1ee5ng 2 l\u1ea7n sao cho: C\u00f3 m\u1ed9t ch\u1eef s\u1ed1 \u1edf gi\u1eefa hai ch\u1eef s\u1ed1 1; c\u00f3 hai ch\u1eef s\u1ed1 \u1edf gi\u1eefa hai ch\u1eef s\u1ed1 2; c\u00f3 3 ch\u1eef s\u1ed1 \u1edf gi\u1eefa hai ch\u1eef s\u1ed1 3; v\u00e0 c\u00f3 b\u1ed1n ch\u1eef s\u1ed1 \u1edf gi\u1eefa hai ch\u1eef s\u1ed1 4.<\/p>\n

-> \u0110\u00e1p \u00e1n:<\/strong> 41312432 v\u00e0 23421314<\/p>\n

 <\/p>\n

C\u00e2u h\u1ecfi 23<\/strong>: N\u0103m 2014 c\u00f3 t\u00ednh ch\u1ea5t l\u00e0 ch\u1eef s\u1ed1 h\u00e0ng \u0111\u01a1n v\u1ecb g\u1ea5p 2 l\u1ea7n ch\u1eef s\u1ed1 h\u00e0ng ngh\u00ecn. H\u1ecfi sau bao nhi\u00eau n\u0103m n\u1eefa th\u00ec l\u1ea1i c\u00f3 1 n\u0103m c\u00f3 t\u00ednh ch\u1ea5t nh\u01b0 v\u1eady?<\/p>\n

-> \u0110\u00e1p \u00e1n: <\/strong>Sau 10 n\u0103m n\u1eefa l\u00e0 n\u0103m 2024<\/p>\n

 <\/p>\n

C\u00e2u h\u1ecfi 24<\/strong>:<\/p>\n

\u0110\u00e0n c\u00f2 bay l\u1ea3 bay la<\/p>\n

Bay qua c\u1eeda s\u1ed5 l\u1edbp 3 ch\u00fang m\u00ecnh<\/p>\n

S\u1ed1 c\u00f2 c\u1ed9ng s\u1ed1 h\u1ecdc sin<\/p>\n

B\u1eb1ng t\u00e1m m\u01b0\u01a1i m\u1ed1t \u0111\u1ed1 m\u00ecnh, \u0111\u1ed1 ta<\/p>\n

S\u1ed1 c\u00f2, s\u1ed1 h\u1ecdc sinh l\u00e0<\/p>\n

Hai s\u1ed1 li\u00ean ti\u1ebfp \u0111\u00e2y m\u00e0 b\u1ea1n \u01a1i!<\/p>\n

\u0110\u1ed1 vui v\u1eeba h\u1ecdc v\u1eeba ch\u01a1i<\/p>\n

S\u1ed1 c\u00f2 l\u00e0 m\u1ea5y, tr\u1ea3 l\u1eddi nhanh nhanh?<\/p>\n

-> \u0110\u00e1p \u00e1n: <\/strong>Theo \u0111\u1ec1 b\u00e0i ta c\u00f3: 81 = 40 + 41. V\u1eady s\u1ed1 c\u00f2 l\u00e0 40 (con), s\u1ed1 h\u1ecdc sinh l\u00e0: 41 (b\u1ea1n)<\/p>\n

 <\/p>\n

C\u00e2u h\u1ecfi 25<\/strong>: N\u0103m nay, th\u1ecf Rabby l\u00ean 8 tu\u1ed5i. S\u1ed1 tu\u1ed5i c\u1ee7a th\u1ecf m\u1eb9 g\u1ea5p 4 l\u1ea7n s\u1ed1 tu\u1ed5i c\u1ee7a Rabby. H\u1ecfi sau bao nhi\u00eau n\u0103m n\u1eefa th\u00ec tu\u1ed5i c\u1ee7a th\u1ecf m\u1eb9 g\u1ea5p 3 l\u1ea7n tu\u1ed5i c\u1ee7a Rabby?<\/p>\n

-> \u0110\u00e1p \u00e1n:<\/strong> 4 n\u0103m<\/p>\n

 <\/p>\n

C\u00e2u h\u1ecfi 26<\/strong>: 2 con v\u1ecbt \u0111i tr\u01b0\u1edbc 2 con v\u1ecbt, 2 con v\u1ecbt \u0111i sau 2 con v\u1ecbt, 2 con v\u1ecbt \u0111i gi\u1eefa 2 con v\u1ecbt. H\u1ecfi c\u00f3 m\u1ea5y con v\u1ecbt?<\/p>\n

-> \u0110\u00e1p \u00e1n:<\/strong> 4 con v\u1ecbt<\/p>\n

 <\/p>\n

C\u00e2u h\u1ecfi 27<\/strong>: An mua t\u1ea5t c\u1ea3 120 vi\u00ean k\u1eb9o g\u1ed3m k\u1eb9o d\u00e2u, k\u1eb9o cam v\u00e0 k\u1eb9o s\u1eefa. S\u1ed1 k\u1eb9o d\u00e2u th\u00ec g\u1ea5p \u0111\u00f4i s\u1ed1 k\u1eb9o cam. S\u1ed1 k\u1eb9o cam h\u01a1n s\u1ed1 k\u1eb9o s\u1eefa l\u00e0 4 vi\u00ean. H\u1ecfi An c\u00f3 bao nhi\u00eau k\u1eb9o cam?<\/p>\n

-> \u0110\u00e1p \u00e1n:<\/strong> 31 vi\u00ean k\u1eb9o<\/p>\n

\n

> BST c\u00e2u h\u1ecfi \u0111\u1ed1 vui:<\/p>\n