1001 toán tư duy lớp 4

["1001 B\u00c0I TO\u00c1N T\u01af DUY C\u00e2u 23. Quy \u0111\u1ed3ng hai ph\u00e2n s\u1ed1 $ v\u00e0 % v\u1edbi m\u1eabu s\u1ed1 chung l\u00e0 81. # $' C\u00e2u 24. T\u00ednh: C\u00e2u 25. T\u00ednh: 51","\u0110\u00e1p \u00e1n ch\u1ee7 \u0111\u1ec1 3 1C 6C 11B 16A 21D 2C 7B 12D 17D 22C 3B 8D 13C 18C 23D 4C 9D 14A 19D 24A 5A 10A 15D 20B 25C T\u1ea3i App Hoc247 Kids \u0111\u1ec3 xem video h\u01b0\u1edbng d\u1eabn gi\u1ea3i chi ti\u1ebft nh\u00e9! 52","CH\u1ee6 \u0110\u1ec0 4: C\u00c1C D\u1ea0NG TO\u00c1N \u0110\u1eb6C BI\u1ec6T Ki\u1ebfn th\u1ee9c c\u1ea7n nh\u1edb B\u00e0i to\u00e1n trung b\u00ecnh c\u1ed9ng - D\u1ea1ng 1: T\u00ecm trung b\u00ecnh c\u1ed9ng Ph\u01b0\u01a1ng ph\u00e1p gi\u1ea3i B\u01b0\u1edbc 1: X\u00e1c \u0111\u1ecbnh s\u1ed1 c\u00e1c s\u1ed1 h\u1ea1ng c\u00f3 trong b\u00e0i to\u00e1n. B\u01b0\u1edbc 2: T\u00ednh t\u1ed5ng c\u00e1c s\u1ed1 h\u1ea1ng v\u1eeba t\u00ecm \u0111\u01b0\u1ee3c. B\u01b0\u1edbc 3: Trung b\u00ecnh c\u1ed9ng = \u201cT\u1ed5ng c\u1ee7a c\u00e1c s\u1ed1 \u0111\u00f3\u201d chia cho \u201cs\u1ed1 c\u00e1c s\u1ed1 h\u1ea1ng\u201d. V\u00ed d\u1ee5: Tr\u01b0\u1eddng ti\u1ec3u h\u1ecdc L\u01b0\u01a1ng Th\u1ebf Vinh c\u00f3 3 l\u1edbp tham gia tr\u1ed3ng c\u00e2y. L\u1edbp 4A tr\u1ed3ng \u0111\u01b0\u1ee3c 17 c\u00e2y, l\u1edbp 4B tr\u1ed3ng \u0111\u01b0\u1ee3c 13 c\u00e2y, l\u1edbp 4C tr\u1ed3ng \u0111\u01b0\u1ee3c 15 c\u00e2y. H\u1ecfi trung b\u00ecnh m\u1ed7i l\u1edbp tr\u1ed3ng \u0111\u01b0\u1ee3c bao nhi\u00eau c\u00e2y? B\u00e0i gi\u1ea3i C\u00f3 3 l\u1edbp tham gia tr\u1ed3ng c\u00e2y s\u1ed1 c\u00e1c s\u1ed1 h\u1ea1ng l\u00e0 3 T\u1ed5ng s\u1ed1 c\u00e2y c\u1ea3 ba l\u1edbp tr\u1ed3ng l\u00e0: 17 + 13 + 15 = 45 (c\u00e2y) Trung b\u00ecnh m\u1ed7i l\u1edbp tr\u1ed3ng \u0111\u01b0\u1ee3c s\u1ed1 c\u00e2y l\u00e0: 45 : 3 = 15 (c\u00e2y) \u0110\u00e1p s\u1ed1: 15 c\u00e2y 53","Trung b\u00ecnh c\u1ed9ng c\u1ee7a d\u00e3y c\u00e1ch \u0111\u1ec1u b\u1eb1ng: - S\u1ed1 \u1edf ch\u00ednh gi\u1eefa (n\u1ebfu d\u00e3y c\u00f3 c\u00e1c s\u1ed1 h\u1ea1ng l\u00e0 s\u1ed1 l\u1ebb). - Trung b\u00ecnh c\u1ed9ng 2 s\u1ed1 \u1edf gi\u1eefa (n\u1ebfu d\u00e3y c\u00f3 c\u00e1c s\u1ed1 h\u1ea1ng l\u00e0 s\u1ed1 ch\u1eb5n). - Trung b\u00ecnh c\u1ed9ng = (s\u1ed1 \u0111\u1ea7u + s\u1ed1 cu\u1ed1i) : 2 V\u00ed d\u1ee5: T\u00ecm trung b\u00ecnh c\u1ed9ng c\u1ee7a c\u00e1c s\u1ed1 sau: 1, 3, 5, 7, 9 B\u00e0i gi\u1ea3i Trung b\u00ecnh c\u1ed9ng c\u1ee7a c\u00e1c s\u1ed1 l\u00e0: (1 + 3 + 5 + 7 + 9) : 5 = 5 \u0110\u00e1p s\u1ed1: 5 - D\u1ea1ng 2: T\u00ecm gi\u00e1 tr\u1ecb c\u1ee7a trung b\u00ecnh c\u1ed9ng. V\u00ed d\u1ee5: 54","- D\u1ea1ng 3: Nhi\u1ec1u h\u01a1n, \u00edt h\u01a1n trung b\u00ecnh c\u1ed9ng. V\u00ed d\u1ee5: Xe th\u1ee9 nh\u1ea5t ch\u1ee9a \u0111\u01b0\u1ee3c 45 t\u1ea5n h\u00e0ng, xe th\u1ee9 hai ch\u1ee9a \u0111\u01b0\u1ee3c 53 t\u1ea5n h\u00e0ng, xe th\u1ee9 ba ch\u1ee9a \u0111\u01b0\u1ee3c s\u1ed1 h\u00e0ng nhi\u1ec1u h\u01a1n trung b\u00ecnh c\u1ed9ng s\u1ed1 t\u1ea5n h\u00e0ng c\u1ee7a hai xe \u0111\u1ea7u l\u00e0 6 t\u1ea5n. H\u1ecfi xe th\u1ee9 ba ch\u1edf \u0111\u01b0\u1ee3c bao nhi\u00eau t\u1ea5n h\u00e0ng. B\u00e0i gi\u1ea3i Trung b\u00ecnh c\u1ed9ng s\u1ed1 t\u1ea5n h\u00e0ng hai xe \u0111\u1ea7u ch\u1edf \u0111\u01b0\u1ee3c l\u00e0: (45 + 53) : 2 = 49 (t\u1ea5n) S\u1ed1 t\u1ea5n h\u00e0ng xe th\u1ee9 ba ch\u1edf \u0111\u01b0\u1ee3c l\u00e0: 49 + 6 = 55 (t\u1ea5n) \u0110\u00e1p s\u1ed1: 55 t\u1ea5n B\u00e0i to\u00e1n d\u00e3y s\u1ed1 v\u00e0 quy lu\u1eadt D\u00e3y s\u1ed1 - D\u1ea1ng 1: \u0110i\u1ec1n th\u00eam s\u1ed1 h\u1ea1ng v\u00e0o d\u00e3y s\u1ed1. 55","C\u00e1c quy lu\u1eadt th\u01b0\u1eddng g\u1eb7p c\u1ee7a d\u00e3y s\u1ed1: + S\u1ed1 h\u1ea1ng \u0111\u1ee9ng sau b\u1eb1ng s\u1ed1 h\u1ea1ng \u0111\u1ee9ng tr\u01b0\u1edbc nh\u00e2n v\u1edbi s\u1ed1 th\u1ee9 t\u1ef1 c\u1ee7a n\u00f3. + M\u1ed7i s\u1ed1 h\u1ea1ng (k\u1ec3 t\u1eeb s\u1ed1 h\u1ea1ng th\u1ee9 2) tr\u1edf \u0111i \u0111\u1ec1u b\u1eb1ng a l\u1ea7n s\u1ed1 li\u1ec1n tr\u01b0\u1edbc n\u00f3. + M\u1ed7i s\u1ed1 h\u1ea1ng (k\u1ec3 t\u1eeb s\u1ed1 h\u1ea1ng th\u1ee9 2) b\u1eb1ng s\u1ed1 h\u1ea1ng \u0111\u1ee9ng tr\u01b0\u1edbc n\u00f3 c\u1ed9ng (ho\u1eb7c tr\u1eeb) v\u1edbi m\u1ed9t s\u1ed1 t\u1ef1 nhi\u00ean n. + M\u1ed7i s\u1ed1 h\u1ea1ng (k\u1ec3 t\u1eeb s\u1ed1 h\u1ea1ng th\u1ee9 3) b\u1eb1ng t\u1ed5ng hai s\u1ed1 h\u1ea1ng \u0111\u1ee9ng li\u1ec1n tr\u01b0\u1edbc n\u00f3. + M\u1ed7i s\u1ed1 h\u1ea1ng (k\u1ec3 t\u1eeb s\u1ed1 h\u1ea1ng th\u1ee9 4) b\u1eb1ng t\u1ed5ng c\u1ee7a s\u1ed1 h\u1ea1ng \u0111\u1ee9ng tr\u01b0\u1edbc n\u00f3 c\u1ed9ng v\u1edbi s\u1ed1 t\u1ef1 nhi\u00ean b r\u1ed3i c\u1ed9ng v\u1edbi s\u1ed1 th\u1ee9 t\u1ef1 c\u1ee7a s\u1ed1 h\u1ea1ng \u1ea5y. V\u00ed d\u1ee5: T\u00ecm gi\u00e1 tr\u1ecb c\u1ee7a c\u00e1c con v\u1eadt trong d\u00e3y s\u1ed1 sau. B\u00e0i gi\u1ea3i Ta th\u1ea5y: 1 + 2 = 3 ; 2 + 3 = 5 ; 3 + 5 = 8 K\u1ec3 t\u1eeb s\u1ed1 h\u1ea1ng th\u1ee9 3 tr\u1edf \u0111i m\u1ed7i s\u1ed1 h\u1ea1ng b\u1eb1ng t\u1ed5ng c\u1ee7a hai s\u1ed1 h\u1ea1ng \u0111\u1ee9ng li\u1ec1n tr\u01b0\u1edbc n\u00f3. 5 + 8 = 13 8 + 13 = 21 13 + 21 = 34 V\u1eady 56","- D\u1ea1ng 2: T\u00ecm s\u1ed1 s\u1ed1 h\u1ea1ng c\u1ee7a d\u00e3y s\u1ed1 c\u00e1ch \u0111\u1ec1u: + C\u00f4ng th\u1ee9c 1: S\u1ed1 c\u00e1c s\u1ed1 h\u1ea1ng c\u1ee7a d\u00e3y = s\u1ed1 kho\u1ea3ng c\u00e1ch + 1. V\u00ed d\u1ee5: Vi\u1ebft c\u00e1c s\u1ed1 l\u1ebb li\u00ean ti\u1ebfp t\u1eeb 211. S\u1ed1 cu\u1ed1i c\u00f9ng l\u00e0 971. H\u1ecfi vi\u1ebft \u0111\u01b0\u1ee3c bao nhi\u00eau s\u1ed1? B\u00e0i gi\u1ea3i S\u1ed1 cu\u1ed1i c\u00e1ch s\u1ed1 \u0111\u1ea7u s\u1ed1 \u0111\u01a1n v\u1ecb l\u00e0: 971 \u2013 211 = 760 (\u0111\u01a1n v\u1ecb) 760 \u0111\u01a1n v\u1ecb c\u00f3 s\u1ed1 kho\u1ea3ng c\u00e1ch l\u00e0: 760 : 2 = 380 (kho\u1ea3ng c\u00e1ch) S\u1ed1 s\u1ed1 h\u1ea1ng c\u1ee7a d\u00e3y s\u1ed1 tr\u00ean l\u00e0: 380 + 1 = 381 (s\u1ed1) + C\u00f4ng th\u1ee9c 2: S\u1ed1 c\u00e1c s\u1ed1 h\u1ea1ng c\u1ee7a d\u00e3y = (S\u1ed1 h\u1ea1ng l\u1edbn nh\u1ea5t \u2013 S\u1ed1 h\u1ea1ng nh\u1ecf nh\u1ea5t ) : kho\u1ea3ng c\u00e1ch + 1. V\u00ed d\u1ee5: T\u00ecm s\u1ed1 s\u1ed1 h\u1ea1ng c\u1ee7a d\u00e3y s\u1ed1 sau. 1, 4, 7, 10, 13, 16, 19, \u2026, 94, 97, 100 X\u00e1c \u0111\u1ecbnh B\u00e0i gi\u1ea3i - S\u1ed1 \u0111\u1ea7u: S\u1ed1 s\u1ed1 h\u1ea1ng c\u1ee7a d\u00e3y s\u1ed1 l\u00e0: - S\u1ed1 cu\u1ed1i: (100 \u2013 1) : 3 + 1 = 34 (s\u1ed1 h\u1ea1ng) - Kho\u1ea3ng c\u00e1ch: \u0110\u00e1p s\u1ed1: 34 s\u1ed1 h\u1ea1ng 57","- D\u1ea1ng 3: T\u00ecm t\u1ed5ng d\u00e3y s\u1ed1 c\u00e1ch \u0111\u1ec1u. Ph\u01b0\u01a1ng ph\u00e1p gi\u1ea3i V\u00ed d\u1ee5: T\u00ednh t\u1ed5ng c\u00e1c s\u1ed1 t\u1ef1 nhi\u00ean ch\u1eb5n t\u1eeb 0 \u0111\u1ebfn 100. D\u00e3y h\u00ecnh V\u00ed d\u1ee5: H\u1ecfi c\u00f3 bao nhi\u00eau que di\u00eam trong h\u00ecnh th\u1ee9 10. 58","B\u00e0i gi\u1ea3i B\u00e0i to\u00e1n trang s\u00e1ch - D\u1ea1ng 1: T\u00ecm s\u1ed1 ch\u1eef s\u1ed1 c\u1ee7a d\u00e3y khi bi\u1ebft s\u1ed1 s\u1ed1 h\u1ea1ng Ph\u01b0\u01a1ng ph\u00e1p gi\u1ea3i T\u00ednh s\u1ed1 ch\u1eef s\u1ed1 t\u1eeb trang 1 \u2013 9; 10 \u2013 99; 101 \u2013 999;\u2026 Sau \u0111\u00f3 c\u1ed9ng t\u1ea5t c\u1ea3 l\u1ea1i ta s\u1ebd \u0111\u01b0\u1ee3c \u0111\u00e1p s\u1ed1. \u00c1p d\u1ee5ng c\u00e1c c\u00f4ng th\u1ee9c t\u00ednh: S\u1ed1 s\u1ed1 h\u1ea1ng = (S\u1ed1 cu\u1ed1i \u2013 S\u1ed1 \u0111\u1ea7u) : Kho\u1ea3ng c\u00e1ch gi\u1eefa hai s\u1ed1 + 1 V\u00ed d\u1ee5: \u0110\u1ec3 \u0111\u00e1nh s\u1ed1 trang c\u1ee7a m\u1ed9t quy\u1ec3n s\u00e1ch d\u00e0y 238 trang c\u1ea7n d\u00f9ng bao nhi\u00eau ch\u1eef s\u1ed1? B\u00e0i gi\u1ea3i T\u1eeb 1 \u0111\u1ebfn 9 c\u00f3: (9 \u2013 1) : 1 + 1 = 9 (s\u1ed1 c\u00f3 m\u1ed9t ch\u1eef s\u1ed1) T\u1eeb 10 \u0111\u1ebfn 99 c\u00f3: (99 \u2013 10) : 1 + 1 = 90 (s\u1ed1 c\u00f3 hai ch\u1eef s\u1ed1) 59","T\u1eeb 100 \u0111\u1ebfn 238 c\u00f3: (238 \u2013 100) : 1 + 1 = 139 (s\u1ed1 c\u00f3 ba ch\u1eef s\u1ed1) V\u1eady 238 trang c\u1ea7n d\u00f9ng s\u1ed1 ch\u1eef s\u1ed1 l\u00e0: 1 x 9 + 2 x 90 + 3 x 139 = 606 (s\u1ed1 ch\u1eef s\u1ed1) \u0110\u00e1p s\u1ed1: 606 s\u1ed1 ch\u1eef s\u1ed1 - D\u1ea1ng 2: T\u00ecm s\u1ed1 s\u1ed1 h\u1ea1ng khi bi\u1ebft ch\u1eef s\u1ed1. V\u00ed d\u1ee5: \u0110\u1ec3 \u0111\u00e1nh s\u1ed1 trang 1 quy\u1ec3n s\u00e1ch ng\u01b0\u1eddi ta d\u00f9ng h\u1ebft 435 ch\u1eef s\u1ed1. H\u1ecfi quy\u1ec3n s\u00e1ch \u0111\u00f3 c\u00f3 bao nhi\u00eau trang? S\u1ed1 trang s\u00e1ch c\u00f3 1 ch\u1eef s\u1ed1 l\u00e0 9 s\u1ed1 n\u00ean: 1 x 9 = 9 (ch\u1eef s\u1ed1) S\u1ed1 trang s\u00e1ch c\u00f3 2 ch\u1eef s\u1ed1 l\u00e0 90 s\u1ed1 n\u00ean: 2 x 90 = 180 (ch\u1eef s\u1ed1) S\u1ed1 ch\u1eef s\u1ed1 \u0111\u1ec3 \u0111\u00e1nh s\u1ed1 trang s\u00e1ch c\u00f3 3 ch\u1eef s\u1ed1 l\u00e0: 435 \u2013 9 \u2013 180 = 246 (ch\u1eef s\u1ed1) 246 ch\u1eef s\u1ed1 th\u00ec \u0111\u00e1nh \u0111\u01b0\u1ee3c s\u1ed1 trang c\u00f3 3 ch\u1eef s\u1ed1 l\u00e0: 246 : 3 = 82 (trang) Quy\u1ec3n s\u00e1ch \u0111\u00f3 c\u00f3 s\u1ed1 trang l\u00e0: 9 + 90 + 82 = 181 (trang) \u0110\u00e1p s\u1ed1: 181 trang 60","Luy\u1ec7n t\u1eadp C\u00e2u 1. Vi\u1ebft 20 s\u1ed1 l\u1ebb li\u00ean ti\u1ebfp, s\u1ed1 cu\u1ed1i c\u00f9ng l\u00e0 3011. S\u1ed1 \u0111\u1ea7u ti\u00ean l\u00e0 s\u1ed1 n\u00e0o? C\u00e2u 2. T\u00ednh t\u1ed5ng sau S = 4 + 7 + 10 + 13 + \u2026 + 2014 + 2017 C\u00e2u 3. Ng\u01b0\u1eddi ta d\u00f9ng 843 ch\u1eef s\u1ed1 \u0111\u1ec3 \u0111\u00e1nh s\u1ed1 trang m\u1ed9t quy\u1ec3n truy\u1ec7n. H\u1ecfi quy\u1ec3n truy\u1ec7n \u0111\u00f3 c\u00f3 bao nhi\u00eau trang? 61","C\u00e2u 4. Bi\u1ebft $ tu\u1ed5i c\u1ee7a B\u00ecnh 6 n\u0103m tr\u01b0\u1edbc b\u1eb1ng $ tu\u1ed5i c\u1ee7a B\u00ecnh 6 ( - n\u0103m t\u1edbi. H\u1ecfi B\u00ecnh hi\u1ec7n nay bao nhi\u00eau tu\u1ed5i ? C\u00e2u 5. M\u1ed9t gi\u00e1 s\u00e1ch c\u00f3 hai ng\u0103n, s\u1ed1 s\u00e1ch ng\u0103n tr\u00ean b\u1eb1ng ( s\u1ed1 s\u00e1ch & ng\u0103n d\u01b0\u1edbi. N\u1ebfu chuy\u1ec3n 12 quy\u1ec3n s\u00e1ch t\u1eeb ng\u0103n tr\u00ean xu\u1ed1ng ng\u0103n d\u01b0\u1edbi th\u00ec s\u1ed1 s\u00e1ch \u1edf ng\u0103n tr\u00ean b\u1eb1ng $ s\u1ed1 s\u00e1ch \u1edf ng\u0103n d\u01b0\u1edbi. T\u00ednh s\u1ed1 & s\u00e1ch m\u1ed7i ng\u0103n. A. Tr\u00ean: 33 quy\u1ec3n; D\u01b0\u1edbi: 47 quy\u1ec3n B. Tr\u00ean: 32 quy\u1ec3n; D\u01b0\u1edbi: 48 quy\u1ec3n C. Tr\u00ean: 31 quy\u1ec3n; D\u01b0\u1edbi: 49 quy\u1ec3n C\u00e2u 6. N\u0103m nay, anh 15 tu\u1ed5i, c\u00f2n em 6 tu\u1ed5i. H\u1ecfi sau bao nhi\u00eau n\u0103m n\u1eefa th\u00ec t\u1ed5ng s\u1ed1 tu\u1ed5i c\u1ee7a hai anh em l\u00e0 29 tu\u1ed5i? 62","C\u00e2u 7. H\u1ecfi c\u00f3 bao nhi\u00eau que di\u00eam trong h\u00ecnh th\u1ee9 99? A. 563 que di\u00eam B. 496 que di\u00eam C. 586 que di\u00eam C\u00e2u 8. H\u00ecnh 6 g\u1ed3m bao nhi\u00eau h\u00ecnh ch\u1eef nh\u1eadt? A. 21 h\u00ecnh ch\u1eef nh\u1eadt B. 15 h\u00ecnh ch\u1eef nh\u1eadt C. 24 h\u00ecnh ch\u1eef nh\u1eadt C\u00e2u 9. B\u00ecnh c\u00f3 8 quy\u1ec3n v\u1edf, Nguy\u00ean c\u00f3 4 quy\u1ec3n v\u1edf. Mai c\u00f3 s\u1ed1 v\u1edf \u00edt h\u01a1n trung b\u00ecnh c\u1ed9ng c\u1ee7a c\u1ea3 ba b\u1ea1n l\u00e0 2 quy\u1ec3n. H\u1ecfi s\u1ed1 v\u1edf c\u1ee7a Mai l\u00e0 bao nhi\u00eau? A. 2 quy\u1ec3n v\u1edf B. 4 quy\u1ec3n v\u1edf C. 6 quy\u1ec3n v\u1edf 63","C\u00e2u 10. B\u1ed1 n\u0103m nay 42 tu\u1ed5i, con b\u1eb1ng & tu\u1ed5i c\u1ee7a b\u1ed1. H\u1ecfi sau 6 * n\u0103m n\u1eefa, tu\u1ed5i con s\u1ebd l\u00e0 bao nhi\u00eau tu\u1ed5i? C\u00e2u 11. T\u00ednh t\u1ed5ng 50 s\u1ed1 l\u1ebb li\u00ean ti\u1ebfp bi\u1ebft s\u1ed1 l\u1ebb l\u1edbn nh\u1ea5t trong d\u00e3y \u0111\u00f3 l\u00e0 2013? C\u00e2u 12. T\u00ecm hai s\u1ed1 t\u1ef1 nhi\u00ean c\u00f3 t\u1ed5ng b\u1eb1ng 675, bi\u1ebft gi\u1eefa hai s\u1ed1 \u0111\u00f3 c\u00f3 t\u1ea5t c\u1ea3 4 s\u1ed1 ch\u1eb5n? 64","C\u00e2u 13. Cha h\u01a1n con 32 tu\u1ed5i. Sau 4 n\u0103m n\u1eefa th\u00ec tu\u1ed5i cha g\u1ea5p ba l\u1ea7n tu\u1ed5i con. H\u1ecfi tu\u1ed5i cha v\u00e0 tu\u1ed5i con hi\u1ec7n nay l\u00e0 bao nhi\u00eau tu\u1ed5i? A. Cha: 44 tu\u1ed5i ; B. Cha: 45 tu\u1ed5i ; C. Cha: 46 tu\u1ed5i ; Con: 12 tu\u1ed5i Con: 11 tu\u1ed5i Con: 10 tu\u1ed5i C\u00e2u 14. Nh\u1edd m\u00e1y \u0111\u1ebfm ng\u01b0\u1eddi ta ghi \u0111\u01b0\u1ee3c c\u00e1c trang s\u00e1ch c\u1ee7a m\u1ed9t quy\u1ec3n s\u00e1ch c\u1ea7n t\u1ea5t c\u1ea3 1392 ch\u1eef s\u1ed1 ghi trang. H\u1ecfi quy\u1ec3n s\u00e1ch c\u00f3 t\u1ea5t c\u1ea3 bao nhi\u00eau trang? A. 500 trang B. 611 trang C. 450 trang 65","C\u00e2u 15. M\u1ed9t cu\u1ed1n s\u00e1ch b\u1ecb r\u01a1i m\u1ea5t m\u1ed9t s\u1ed1 t\u1edd. Trang b\u1ecb r\u01a1i th\u1ee9 nh\u1ea5t c\u00f3 s\u1ed1 387, c\u00f2n trang cu\u1ed1i c\u0169ng g\u1ed3m ba ch\u1eef s\u1ed1 3; 8; 7 nh\u01b0ng \u0111\u01b0\u1ee3c vi\u1ebft theo m\u1ed9t th\u1ee9 t\u1ef1 kh\u00e1c. H\u1ecfi cu\u1ed1n s\u00e1ch c\u00f3 bao nhi\u00eau t\u1edd b\u1ecb r\u01a1i ra? C\u00e2u 16. B\u1ea1n Anan tham gia thi gi\u1ea3i 30 c\u00e2u h\u1ecfi trong cu\u1ed9c thi gi\u1ea3i to\u00e1n qua m\u1ea1ng. M\u1ed7i c\u00e2u tr\u1ea3 l\u1eddi \u0111\u00fang \u0111\u01b0\u1ee3c 5 \u0111i\u1ec3m. M\u1ed7i c\u00e2u tr\u1ea3 l\u1eddi sai m\u1ea5t 10 \u0111i\u1ec3m. Cu\u1ed1i c\u00f9ng b\u1ea1n Anan \u0111\u01b0\u1ee3c 105 \u0111i\u1ec3m. H\u1ecfi b\u1ea1n Anan \u0111\u1ea1t \u0111\u01b0\u1ee3c bao nhi\u00eau c\u00e2u tr\u1ea3 l\u1eddi \u0111\u00fang? A. 36 c\u00e2u \u0111\u00fang. B. 43 c\u00e2u \u0111\u00fang. C. 27 c\u00e2u \u0111\u00fang. C\u00e2u 17. Trong m\u1ed9t b\u1eefa ti\u1ec7c, c\u00f3 t\u1ea5t c\u1ea3 100 ng\u01b0\u1eddi l\u1edbn v\u00e0 tr\u1ebb em. Trong khi m\u1ed9t ng\u01b0\u1eddi l\u1edbn c\u00f3 th\u1ec3 \u0103n h\u1ebft 3 chi\u1ebfc b\u00e1nh s\u1eefa, th\u00ec 3 tr\u1ebb em m\u1edbi \u0103n h\u1ebft \u0111\u01b0\u1ee3c m\u1ed9t c\u00e1i. Sau b\u1eefa ti\u1ec7c, m\u1ecdi ng\u01b0\u1eddi \u0103n h\u1ebft 100 chi\u1ebfc b\u00e1nh s\u1eefa. H\u1ecfi c\u00f3 bao nhi\u00eau ng\u01b0\u1eddi l\u1edbn, bao nhi\u00eau tr\u1ebb em tham d\u1ef1? A. 75 tr\u1ebb em, 25 ng\u01b0\u1eddi l\u1edbn. B. 76 tr\u1ebb em, 24 ng\u01b0\u1eddi l\u1edbn. C. 77 tr\u1ebb em, 23 ng\u01b0\u1eddi l\u1edbn. 66","1001 B\u00c0I TO\u00c1N T\u01af DUY C\u00e2u 18. C\u00f3 8 s\u1ecdt \u0111\u1ef1ng \u0111\u01b0\u1ee3c t\u1ea5t c\u1ea3 1120 qu\u1ea3 v\u1eeba cam v\u1eeba qu\u00fdt. M\u1ed9t s\u1ecdt cam \u0111\u1ef1ng \u0111\u01b0\u1ee3c 75 qu\u1ea3, m\u1ed9t s\u1ecdt qu\u00fdt \u0111\u1ef1ng \u0111\u01b0\u1ee3c 179 qu\u1ea3. H\u1ecfi m\u1ed7i lo\u1ea1i c\u00f3 bao nhi\u00eau qu\u1ea3? A. 895 qu\u1ea3 qu\u00fdt v\u00e0 225 qu\u1ea3 cam B. 859 qu\u1ea3 qu\u00fdt v\u00e0 252 qu\u1ea3 cam C. 958 qu\u1ea3 qu\u00fdt v\u00e0 252 qu\u1ea3 cam C\u00e2u 19. C\u00f3 10 xe ch\u1edf g\u1ea1o g\u1ed3m 2 lo\u1ea1i. Lo\u1ea1i I ch\u1edf \u0111\u01b0\u1ee3c 45 t\u1ea1 v\u00e0 lo\u1ea1i II ch\u1edf \u0111\u01b0\u1ee3c 32 t\u1ea1. T\u1ea5t c\u1ea3 ch\u1edf \u0111\u01b0\u1ee3c 39 t\u1ea5n 8 t\u1ea1 g\u1ea1o. H\u1ecfi c\u00f3 bao nhi\u00eau xe m\u1ed7i lo\u1ea1i? A. Lo\u1ea1i I: 7 xe ; Lo\u1ea1i II: 3 xe B. Lo\u1ea1i I: 6 xe ; Lo\u1ea1i II: 4 xe C. Lo\u1ea1i I: 5 xe ; Lo\u1ea1i II: 5 xe C\u00e2u 20. H\u00e3y ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang! A. 45 que B. 54 que C. 62 que 67","1001 B\u00c0I TO\u00c1N T\u01af DUY C\u00e2u 21. Cho d\u00e3y s\u1ed1: 6 + 8 + 10 +. .. + 1998. H\u00e3y t\u00ecm s\u1ed1 s\u1ed1 h\u1ea1ng c\u1ee7a d\u00e3y s\u1ed1 \u0111\u00f3. A. 997 s\u1ed1 h\u1ea1ng B. 989 s\u1ed1 h\u1ea1ng C. 978 s\u1ed1 h\u1ea1ng C\u00e2u 22. M\u1ed9t \u0111\u1ed9i xe ch\u1edf h\u00e0ng v\u00e0o kho. Trong 4 ng\u00e0y \u0111\u1ea7u, m\u1ed7i ng\u00e0y ch\u1edf v\u00e0o 45 t\u1ea5n h\u00e0ng. Trong 2 ng\u00e0y sau, m\u1ed7i ng\u00e0y ch\u1edf v\u00e0o 24 t\u1ea5n h\u00e0ng. H\u1ecfi trung b\u00ecnh m\u1ed7i ng\u00e0y kho nh\u1eadn \u0111\u01b0\u1ee3c bao nhi\u00eau t\u1ea5n h\u00e0ng? C\u00e2u 23. Trong 5 ng\u00e0y, trung b\u00ecnh m\u1ed7i ng\u00e0y c\u1eeda h\u00e0ng b\u00e1n 420m v\u1ea3i. Trong 2 ng\u00e0y \u0111\u1ea7u, m\u1ed7i ng\u00e0y b\u00e1n 360m v\u1ea3i. H\u1ecfi trung b\u00ecnh m\u1ed7i ng\u00e0y c\u00f2n l\u1ea1i c\u1eeda h\u00e0ng b\u00e1n bao nhi\u00eau m\u00e9t v\u1ea3i? A. 460m B. 478m C. 560m 68","1001 B\u00c0I TO\u00c1N T\u01af DUY C\u00e2u 24. T\u00ecm 4 s\u1ed1 ch\u1eb5n li\u00ean ti\u1ebfp c\u00f3 trung b\u00ecnh c\u1ed9ng l\u00e0 2003. C\u00e2u 25. Trung b\u00ecnh c\u1ed9ng c\u1ee7a hai s\u1ed1 l\u00e0 15. Bi\u1ebft m\u1ed9t s\u1ed1 l\u00e0 19. T\u00ecm s\u1ed1 c\u00f2n l\u1ea1i? 69","\u0110\u00e1p \u00e1n ch\u1ee7 \u0111\u1ec1 4 1A 6A 11B 16A 21A 2B 7B 12C 17A 22C 3D 8A 13A 18A 23A 4A 9A 14A 19B 24B 5B 10C 15A 20C 25A T\u1ea3i App Hoc247 Kids \u0111\u1ec3 xem video h\u01b0\u1edbng d\u1eabn gi\u1ea3i chi ti\u1ebft nh\u00e9! 70","CH\u1ee6 \u0110\u1ec0 5: T\u00ccM QUY LU\u1eacT. T\u00cdNH NG\u01af\u1ee2C. G\u00c0 V\u00c0 TH\u1ece Ki\u1ebfn th\u1ee9c c\u1ea7n nh\u1edb D\u00e3y s\u1ed1 Fibonacci - D\u00e3y Fibonacci l\u00e0 d\u00e3y v\u00f4 h\u1ea1n c\u00e1c s\u1ed1 t\u1ef1 nhi\u00ean b\u1eaft \u0111\u1ea7u b\u1eb1ng 1 v\u00e0 1, sau \u0111\u00f3 c\u00e1c s\u1ed1 ti\u1ebfp theo s\u1ebd b\u1eb1ng t\u1ed5ng c\u1ee7a 2 s\u1ed1 li\u1ec1n tr\u01b0\u1edbc n\u00f3. - C\u1ee5 th\u1ec3, c\u00e1c s\u1ed1 \u0111\u1ea7u ti\u00ean c\u1ee7a d\u00e3y Fibonacci l\u00e0 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, 233, 377, 610... 71","Quy lu\u1eadt s\u1ed1 - Hi\u1ec7u s\u1ed1 kh\u00f4ng \u0111\u1ed5i. V\u00ed d\u1ee5: T\u00ecm s\u1ed1 c\u00f2n thi\u1ebfu trong d\u00e3y s\u1ed1 sau: 4, 9, 14, 19, ___ , ___ B\u00e0i gi\u1ea3i Ta th\u1ea5y: 4 + 5 = 9 ; 9 + 5 = 14 ; 14 + 5 = 19 19 + 5 = 24 ; 24 + 5 = 29 V\u1eady: 4, 9, 14, 19, 24, 29 - Hi\u1ec7u t\u0103ng d\u1ea7n th\u00eam 2. V\u00ed d\u1ee5: T\u00ecm s\u1ed1 c\u00f2n thi\u1ebfu trong d\u00e3y s\u1ed1 sau: 11, 15, 21, 29, 39, ___, ___ B\u00e0i gi\u1ea3i Ta th\u1ea5y: Ta c\u00f3: V\u1eady: 11, 15, 21, 29, 39, 51, 65 72","- Hi\u1ec7u t\u0103ng d\u1ea7n th\u00eam 1. V\u00ed d\u1ee5: T\u00ecm s\u1ed1 c\u00f2n thi\u1ebfu trong d\u00e3y s\u1ed1 sau: 1, 3, 6, 10, 15, ___, ___ B\u00e0i gi\u1ea3i Ta th\u1ea5y: Ta c\u00f3: V\u1eady: 1, 3, 6, 10, 15, 21, 28 - Chia 2 r\u1ed3i tr\u1eeb 2. V\u00ed d\u1ee5: T\u00ecm s\u1ed1 c\u00f2n thi\u1ebfu trong d\u00e3y s\u1ed1 sau: 44, 22, 20, 10, 8, ___, ___ B\u00e0i gi\u1ea3i Ta th\u1ea5y: 73","V\u1eady: 44, 22, 20, 10, 8, 4, 2. - Nh\u00e2n v\u1edbi 101. \u2022 Tr\u01b0\u1eddng h\u1ee3p: 1 s\u1ed1 c\u00f3 2 ch\u1eef s\u1ed1 nh\u00e2n v\u1edbi 101. AB x 101 = AB|AB V\u00ed d\u1ee5: 46 x 101 = 46|46 = 4646 \u2022 Tr\u01b0\u1eddng h\u1ee3p: 1 s\u1ed1 c\u00f3 3 ch\u1eef s\u1ed1 nh\u00e2n v\u1edbi 101 ABC x 101 = AB | A + C | BC V\u00ed d\u1ee5: 135 x 101 = 13 | 1 + 5 | 35 = 13635 368 x 101 = 36| 3+8 | 68 = 36 + 1 | 1 | 68 = 37168 Quy lu\u1eadt h\u00ecnh V\u00ed d\u1ee5: 74","B\u00e0i gi\u1ea3i Ta th\u1ea5y: Ta c\u00f3: V\u1eady: T\u00ednh t\u1ed5ng - Theo nh\u00e0 To\u00e1n h\u1ecdc Gauss. 75","V\u00ed d\u1ee5: T\u00ednh t\u1ed5ng sau: B\u00e0i gi\u1ea3i Ta th\u1ea5y: 1 + 8 = 9 ; 2 + 7 = 9 ; 3 + 6 = 9 ; 4 + 5 = 9 T\u1eeb \u0111\u00f3 suy ra: T\u1ed5ng = 1 c\u1eb7p x s\u1ed1 c\u1eb7p Ta c\u00f3: V\u1eady: T\u1ed5ng = 36 - T\u00ednh t\u1ed5ng c\u1ee7a chu\u1ed7i. Ph\u01b0\u01a1ng ph\u00e1p gi\u1ea3i - B\u01b0\u1edbc 1: X\u00e1c \u0111\u1ecbnh kho\u1ea3ng c\u00e1ch gi\u1eefa hai s\u1ed1 h\u1ea1ng li\u00ean ti\u1ebfp. - B\u01b0\u1edbc 2: T\u00ednh t\u1ed5ng c\u1ee7a s\u1ed1 \u0111\u1ea7u v\u00e0 s\u1ed1 cu\u1ed1i. - B\u01b0\u1edbc 3: T\u00ednh s\u1ed1 s\u1ed1 h\u1ea1ng c\u1ee7a d\u00e3y. S\u1ed1 s\u1ed1 h\u1ea1ng = (S\u1ed1 cu\u1ed1i \u2013 S\u1ed1 \u0111\u1ea7u) : Kho\u1ea3ng c\u00e1ch + 1 - B\u01b0\u1edbc 4: T\u00ednh s\u1ed1 c\u1eb7p. S\u1ed1 c\u1eb7p = S\u1ed1 s\u1ed1 h\u1ea1ng : 2 - B\u01b0\u1edbc 5: T\u00ednh t\u1ed5ng c\u1ee7a chu\u1ed7i T\u1ed5ng c\u1ee7a chu\u1ed7i = T\u1ed5ng c\u1ee7a s\u1ed1 \u0111\u1ea7u v\u00e0 s\u1ed1 cu\u1ed1i x S\u1ed1 c\u1eb7p. B\u00e0i gi\u1ea3i 76","V\u00ed d\u1ee5: T\u00ednh t\u1ed5ng chu\u1ed7i s\u1ed1 sau: 5 + 10 + 15 + \u2026 + 150 + 155 + 160 B\u00e0i gi\u1ea3i Kho\u1ea3ng c\u00e1ch gi\u1eefa hai s\u1ed1 h\u1ea1ng li\u00ean ti\u1ebfp l\u00e0 5. T\u1ed5ng c\u1ee7a s\u1ed1 \u0111\u1ea7u v\u00e0 s\u1ed1 cu\u1ed1i l\u00e0: 5 + 160 = 165 S\u1ed1 s\u1ed1 h\u1ea1ng c\u1ee7a d\u00e3y s\u1ed1 l\u00e0: (160 \u2013 5) : 5 + 1 = 32 (s\u1ed1) D\u00e3y c\u00f3 s\u1ed1 c\u1eb7p s\u1ed1 l\u00e0: 32 : 2 = 16 (c\u1eb7p) T\u1ed5ng c\u1ee7a chu\u1ed7i l\u00e0: 165 x 16 = 2640 \u0110\u00e1p s\u1ed1: 2640 T\u00ednh ng\u01b0\u1ee3c Ph\u01b0\u01a1ng ph\u00e1p gi\u1ea3i - Ta th\u1ef1c hi\u1ec7n li\u00ean ti\u1ebfp t\u1eeb cu\u1ed1i l\u00ean c\u00e1c ph\u00e9p t\u00ednh ng\u01b0\u1ee3c l\u1ea1i v\u1edbi c\u00e1c ph\u00e9p t\u00ednh \u0111\u00e3 cho trong \u0111\u1ec1 b\u00e0i. - L\u01b0u \u00fd: K\u1ebft qu\u1ea3 t\u00ecm \u0111\u01b0\u1ee3c trong b\u01b0\u1edbc tr\u01b0\u1edbc ch\u00ednh l\u00e0 th\u00e0nh ph\u1ea7n \u0111\u00e3 bi\u1ebft c\u1ee7a ph\u00e9p t\u00ednh li\u1ec1n sau \u0111\u00f3. - Sau khi th\u1ef1c hi\u1ec7n h\u1ebft d\u00e3y c\u00e1c ph\u00e9p t\u00ednh ng\u01b0\u1ee3c v\u1edbi c\u00e1c ph\u00e9p t\u00ednh \u0111\u00e3 cho trong \u0111\u1ec1 b\u00e0i, ta nh\u1eadn \u0111\u01b0\u1ee3c k\u1ebft qu\u1ea3 c\u1ea7n t\u00ecm. 77","M\u1ed9t s\u1ed1 ph\u00e9p t\u00ednh ng\u01b0\u1ee3c c\u1ee7a nhau: \u2022 Ph\u00e9p t\u00ednh ng\u01b0\u1ee3c c\u1ee7a ph\u00e9p c\u1ed9ng + (th\u00eam v\u00e0o, t\u0103ng l\u00ean) l\u00e0 ph\u00e9p tr\u1eeb \u2212 (b\u1edbt \u0111i, gi\u1ea3m \u0111i) \u2022 Ph\u00e9p t\u00ednh ng\u01b0\u1ee3c c\u1ee7a ph\u00e9p tr\u1eeb \u2212 l\u00e0 ph\u00e9p c\u1ed9ng + \u2022 Ph\u00e9p t\u00ednh ng\u01b0\u1ee3c c\u1ee7a ph\u00e9p nh\u00e2n \u00d7 (g\u1ea5p l\u00ean bao nhi\u00eau l\u1ea7n) l\u00e0 ph\u00e9p chia : (gi\u1ea3m \u0111i bao nhi\u00eau l\u1ea7n) \u2022 Ph\u00e9p t\u00ednh ng\u01b0\u1ee3c c\u1ee7a ph\u00e9p chia : l\u00e0 ph\u00e9p nh\u00e2n \u00d7 V\u00ed d\u1ee5: \u0110i\u1ec1n s\u1ed1 th\u00edch h\u1ee3p v\u00e0o d\u1ea5u ch\u1ea5m h\u1ecfi: ? B\u00e0i gi\u1ea3i B\u00e0i to\u00e1n G\u00e0 v\u00e0 Th\u1ecf Ph\u01b0\u01a1ng ph\u00e1p gi\u1ea3i - B\u01b0\u1edbc 1: L\u1eadp b\u1ea3ng. - B\u01b0\u1edbc 2: D\u1ef1a v\u00e0o t\u1ed5ng (d\u1eef ki\u1ec7n b\u00e0i to\u00e1n cho) \u0111\u1ec3 tr\u1ea3 l\u1eddi c\u00e2u h\u1ecfi c\u1ee7a b\u00e0i to\u00e1n. 78","V\u00ed d\u1ee5: B\u00e1c n\u00f4ng d\u00e2n nu\u00f4i t\u1ea5t c\u1ea3 30 con g\u00e0 v\u00e0 th\u1ecf. B\u00e1c \u0111\u1ebfm \u0111\u01b0\u1ee3c t\u1ed5ng c\u1ed9ng c\u00f3 100 ch\u00e2n. T\u00ecm s\u1ed1 g\u00e0 v\u00e0 s\u1ed1 th\u1ecf. B\u00e0i gi\u1ea3i Luy\u1ec7n t\u1eadp C\u00e2u 1. B\u00e1c n\u00f4ng d\u00e2n nu\u00f4i t\u1ea5t c\u1ea3 20 con g\u00e0 v\u00e0 th\u1ecf. B\u00e1c \u0111\u1ebfm \u0111\u01b0\u1ee3c t\u1ed5ng c\u1ed9ng c\u00f3 62 ch\u00e2n. T\u00ecm s\u1ed1 g\u00e0 v\u00e0 s\u1ed1 th\u1ecf: 79","C\u00e2u 2. T\u00f4i l\u00e0 m\u1ed9t con s\u1ed1 b\u00ed m\u1eadt. \u0110\u1ea7u ti\u00ean, b\u1ea1n c\u1ed9ng th\u00eam 3 cho t\u00f4i, sau \u0111\u00f3 nh\u00e2n th\u00eam 3 v\u1edbi t\u1ed5ng v\u1eeba \u0111\u1ea1t \u0111\u01b0\u1ee3c, t\u00edch \u0111\u1ea1t \u0111\u01b0\u1ee3c tr\u1eeb \u0111i 3 r\u1ed3i l\u1ea1i chia hi\u1ec7u v\u1eeba t\u1ea1o th\u00e0nh cho 3. K\u1ebft qu\u1ea3 l\u00e0 14. \u0110\u1ed1 b\u1ea1n bi\u1ebft t\u00f4i l\u00e0 s\u1ed1 n\u00e0o? C\u00e2u 3. T\u1eeb 4 s\u1ed1 0; 1; 8; 9 l\u1eadp \u0111\u01b0\u1ee3c bao nhi\u00eau s\u1ed1 c\u00f3 3 ch\u1eef s\u1ed1 kh\u00e1c nhau, chia h\u1ebft cho 2; 3; 5; v\u00e0 9? C\u00e2u 4. B\u00e1c n\u00f4ng d\u00e2n nu\u00f4i t\u1ea5t c\u1ea3 30 con g\u00e0 v\u00e0 th\u1ecf. T\u1ed5ng c\u1ed9ng c\u00f3 100 ch\u00e2n. T\u00ecm s\u1ed1 g\u00e0 v\u00e0 s\u1ed1 th\u1ecf b\u00e1c n\u00f4ng d\u00e2n nu\u00f4i. A. G\u00e0: 10 con; Th\u1ecf: 20 con B. G\u00e0: 12 con; Th\u1ecf: 18 con C. G\u00e0: 14 con; Th\u1ecf: 16 con 80","C\u00e2u 5. C\u00f3 t\u1ea5t c\u1ea3 8 c\u00e2u h\u1ecfi trong m\u1ed9t b\u00e0i thi to\u00e1n, n\u1ebfu tr\u1ea3 l\u1eddi \u0111\u00fang m\u1ed7i c\u00e2u s\u1ebd \u0111\u01b0\u1ee3c c\u1ed9ng 5 \u0111i\u1ec3m, tr\u1ea3 l\u1eddi sai s\u1ebd b\u1ecb tr\u1eeb 2 \u0111i\u1ec3m. H\u1ecfi n\u1ebfu Ron \u0111\u01b0\u1ee3c 33 \u0111i\u1ec3m trong cu\u1ed9c thi to\u00e1n th\u00ec b\u1ea1n \u1ea5y tr\u1ea3 l\u1eddi \u0111\u00fang bao nhi\u00eau c\u00e2u h\u1ecfi? C\u00e2u 6. M\u1ed9t b\u00e0i ki\u1ec3m tra khoa h\u1ecdc g\u1ed3m 30 c\u00e2u h\u1ecfi. M\u1ed7i c\u00e2u tr\u1ea3 l\u1eddi \u0111\u00fang \u0111\u01b0\u1ee3c 3 \u0111i\u1ec3m v\u00e0 m\u1ed7i c\u00e2u tr\u1ea3 l\u1eddi sai b\u1ecb tr\u1eeb 2 \u0111i\u1ec3m. John \u0111\u01b0\u1ee3c 80 \u0111i\u1ec3m. H\u1ecfi b\u1ea1n \u1ea5y \u0111\u00e3 tr\u1ea3 l\u1eddi \u0111\u00fang bao nhi\u00eau c\u00e2u? 81","1001 B\u00c0I TO\u00c1N T\u01af DUY C\u00e2u 7. M\u1ed7i ng\u01b0\u1eddi l\u1edbn l\u1ea5y 2 c\u00e1i b\u00e1nh m\u00ec, m\u1ed7i tr\u1ebb em l\u1ea5y 1 c\u00e1i b\u00e1nh m\u00ec. N\u1ebfu 33 ng\u01b0\u1eddi l\u1edbn v\u00e0 tr\u1ebb em l\u1ea5y t\u1ed5ng c\u1ed9ng 55 c\u00e1i b\u00e1nh m\u00ec. H\u1ecfi c\u00f3 bao nhi\u00eau ng\u01b0\u1eddi l\u1edbn, bao nhi\u00eau tr\u1ebb em? C\u00e2u 8. C\u00f3 t\u1ea5t c\u1ea3 44 gi\u00e1o vi\u00ean v\u00e0 h\u1ecdc sinh \u0111i ra s\u00f4ng ch\u01a1i. M\u1ed9t chi\u1ebfc thuy\u1ec1n l\u1edbn c\u00f3 th\u1ec3 ch\u1edf \u0111\u01b0\u1ee3c 6 ng\u01b0\u1eddi v\u00e0 m\u1ed9t chi\u1ebfc thuy\u1ec1n nh\u1ecf c\u00f3 th\u1ec3 ch\u1edf \u0111\u01b0\u1ee3c 5 ng\u01b0\u1eddi. T\u00ednh s\u1ed1 thuy\u1ec1n l\u1edbn v\u00e0 thuy\u1ec1n nh\u1ecf. C\u00e2u 9. Gi\u00e1 v\u00e9 ng\u01b0\u1eddi l\u1edbn 5$, gi\u00e1 v\u00e9 tr\u1ebb em 3$. S\u1ed1 ti\u1ec1n mua v\u00e9 cho 22 ng\u01b0\u1eddi l\u1edbn v\u00e0 tr\u1ebb em l\u00e0 86$. H\u1ecfi bao nhi\u00eau ng\u01b0\u1eddi l\u1edbn, bao nhi\u00eau tr\u1ebb em? 82","1001 B\u00c0I TO\u00c1N T\u01af DUY C\u00e2u 10. Tr\u00ean n\u00f4ng tr\u1ea1i, c\u00f3 18 con b\u00f2 v\u00e0 v\u1ecbt. C\u00f3 t\u1ea5t c\u1ea3 50 c\u00e1i ch\u00e2n. H\u1ecfi c\u00f3 bao nhi\u00eau con b\u00f2, bao nhi\u00eau con v\u1ecbt? C\u00e2u 11. N\u00f4ng tr\u1ea1i b\u00e1n 3 con th\u1ecf v\u00e0 2 con g\u00e0 v\u1edbi gi\u00e1 47$, 3 con th\u1ecf v\u00e0 3 con g\u00e0 v\u1edbi gi\u00e1 54$. H\u1ecfi gi\u00e1 c\u1ee7a m\u1ed9t con th\u1ecf v\u00e0 m\u1ed9t con g\u00e0 l\u00e0 bao nhi\u00eau? C\u00e2u 12. H\u1ecfi gi\u00e1 1 qu\u1ea3 t\u00e1o l\u00e0 bao nhi\u00eau? bi\u1ebft b\u1ea3ng gi\u00e1 b\u00e1n nh\u01b0 sau: 6 qu\u1ea3 t\u00e1o + 5 qu\u1ea3 cam = 32 \u0111\u00f4-la 8 qu\u1ea3 t\u00e1o + 5 qu\u1ea3 cam = 42 \u0111\u00f4-la 83","1001 B\u00c0I TO\u00c1N T\u01af DUY C\u00e2u 13. C\u00f3 t\u1ea5t c\u1ea3 30 con nh\u1ec7n v\u00e0 chu\u1ed3n chu\u1ed3n v\u1edbi t\u1ed5ng c\u1ed9ng 216 ch\u00e2n. T\u00ecm s\u1ed1 nh\u1ec7n v\u00e0 chu\u1ed3n chu\u1ed3n. C\u00e2u 14. C\u00f3 t\u1ea5t c\u1ea3 26 xe \u00f4 t\u00f4 v\u00e0 xe m\u00f4 t\u00f4 trong b\u00e3i \u0111\u1eadu xe. C\u00f3 80 b\u00e1nh xe. H\u1ecfi c\u00f3 bao nhi\u00eau xe \u00f4 t\u00f4 v\u00e0 xe m\u00f4 t\u00f4? C\u00e2u 15. C\u00f3 t\u1ea5t c\u1ea3 14 xe t\u1ea3i v\u00e0 xe \u00f4 t\u00f4 trong b\u00e3i \u0111\u1eadu xe. C\u00f3 74 b\u00e1nh xe. H\u1ecfi c\u00f3 bao nhi\u00eau xe t\u1ea3i? (1 xe t\u1ea3i 6 b\u00e1nh xe, 1 \u00f4 t\u00f4 c\u00f3 4 b\u00e1nh xe) 84","1001 B\u00c0I TO\u00c1N T\u01af DUY C\u00e2u 16. Samantha c\u00f3 t\u1ea5t c\u1ea3 20 t\u1edd 2$ v\u00e0 5$. T\u1ed5ng s\u1ed1 ti\u1ec1n m\u00e0 c\u1eadu \u1ea5y c\u00f3 l\u00e0 88$. H\u1ecfi Samantha c\u00f3 bao nhi\u00eau t\u1edd 2$ v\u00e0 5$? C\u00e2u 17. \u0110\u1ebfn si\u00eau th\u1ecb, Cindy \u0111\u00e3 ti\u00eau m\u1ed9t n\u1eeda s\u1ed1 ti\u1ec1n c\u1ee7a m\u00ecnh \u0111\u1ec3 mua th\u1ee9c \u0103n. C\u00f4 \u1ea5y ti\u00eau m\u1ed9t n\u1eeda s\u1ed1 ti\u1ec1n c\u00f2n l\u1ea1i v\u00e0 th\u00eam 5 \u0111\u00f4-la n\u1eefa \u0111\u1ec3 mua d\u1ee5ng c\u1ee5 th\u1ec3 thao. Sau c\u00f9ng c\u00f4 \u1ea5y c\u00f2n l\u1ea1i 20 \u0111\u00f4-la. H\u1ecfi ban \u0111\u1ea7u Cindy c\u00f3 bao nhi\u00eau ti\u1ec1n? C\u00e2u 18. M\u1ed9t ng\u01b0\u1eddi b\u00e1n t\u00e1o, l\u1ea7n th\u1ee9 nh\u1ea5t ng\u01b0\u1eddi \u0111\u00f3 b\u00e1n \u0111\u01b0\u1ee3c m\u1ed9t n\u1eeda s\u1ed1 t\u00e1o. L\u1ea7n th\u1ee9 hai, ng\u01b0\u1eddi \u0111\u00f3 b\u00e1n \u0111\u01b0\u1ee3c m\u1ed9t n\u1eeda s\u1ed1 t\u00e1o c\u00f2n l\u1ea1i v\u00e0 2 tr\u00e1i t\u00e1o. Cu\u1ed1i c\u00f9ng c\u00f2n l\u1ea1i 10 tr\u00e1i t\u00e1o. H\u1ecfi l\u00fac \u0111\u1ea7u ng\u01b0\u1eddi \u0111\u00f3 c\u00f3 bao nhi\u00eau tr\u00e1i t\u00e1o? A. B. C. 85","1001 B\u00c0I TO\u00c1N T\u01af DUY C\u00e2u 19. C\u00f3 bao nhi\u00eau s\u1ed1 h\u1ea1ng trong d\u00e3y s\u1ed1 sau: 4, 7, 9, \u2026, 145, 148, 151 C\u00e2u 20. S\u1ed1 h\u1ea1ng th\u1ee9 34 l\u00e0 s\u1ed1 h\u1ea1ng n\u00e0o trong d\u00e3y s\u1ed1 sau: 3, 3, 1, 9, 4, 3, 3, 1, 9, 4, 3, 3, 1, 9, 4, 3, 3, 1, 9, 4... C\u00e2u 21. T\u1ed5ng c\u1ee7a 40 s\u1ed1 h\u1ea1ng \u0111\u1ea7u ti\u00ean: 2, 2, 5, 1, 2, 2, 5, 1, 2, 2, 5, 1,\u2026 86","1001 B\u00c0I TO\u00c1N T\u01af DUY C\u00e2u 22. C\u00f3 16 h\u00e0ng gh\u1ebf trong h\u1ed9i tr\u01b0\u1eddng. M\u1ed7i h\u00e0ng t\u0103ng th\u00eam 4 gh\u1ebf b\u1eaft \u0111\u1ea7u t\u1eeb h\u00e0ng \u0111\u1ea7u ti\u00ean, \u0111\u1ebfn h\u00e0ng cu\u1ed1i c\u00f9ng th\u00ec c\u00f3 95 gh\u1ebf. C\u00f3 t\u1ed5ng c\u1ed9ng bao nhi\u00eau gh\u1ebf trong h\u1ed9i tr\u01b0\u1eddng? A. 1000 gh\u1ebf B. 1040 gh\u1ebf C. 1050 gh\u1ebf C\u00e2u 23. C\u1ee9 2 n\u0103m th\u00ec s\u00e1ch \u0111\u01b0\u1ee3c t\u00e1i b\u1ea3n. Bi\u1ebft l\u1ea7n \u0111\u1ea7u t\u00e1i b\u1ea3n v\u00e0o n\u0103m 2007. H\u1ecfi l\u1ea7n t\u00e1i b\u1ea3n th\u1ee9 8 v\u00e0o n\u0103m n\u00e0o? A. n\u0103m 2011 B. n\u0103m 2019 C. n\u0103m 2021 87","1001 B\u00c0I TO\u00c1N T\u01af DUY C\u00e2u 24. Ch\u1ecdn s\u1ed1 th\u00edch h\u1ee3p v\u00e0o d\u1ea5u h\u1ecfi ch\u1ea5m (?) trong h\u00ecnh. A. 11 B. 21 C. 8 C\u00e2u 25. T\u00ecm h\u00ecnh ch\u01b0a \u0111\u00fang trong c\u00e1c h\u00ecnh sau: 88","1001 B\u00c0I TO\u00c1N T\u01af DUY C\u00e2u 26. S\u1ed1 n\u00e0o d\u01b0\u1edbi \u0111\u00e2y th\u00edch h\u1ee3p \u0111\u1ec3 \u0111i\u1ec1n v\u00e0o d\u1ea5u ? trong h\u00ecnh A. 35 B. 25 C. 16 C\u00e2u 27. \u0110i\u1ec1n s\u1ed1 c\u00f2n thi\u1ebfu trong tam gi\u00e1c d\u01b0\u1edbi \u0111\u00e2y: A. 55, 110, 110, 55 B. 77, 99, 99, 77 C. 55, 55, 55, 55 89","1001 B\u00c0I TO\u00c1N T\u01af DUY C\u00e2u 28. D\u1ef1a theo quy lu\u1eadt em h\u00e3y x\u00e1c \u0111\u1ecbnh c\u00e1c s\u1ed1 c\u00f2n thi\u1ebfu trong d\u00e3y s\u1ed1 sau? A. 1536, 768, 384, 192 B. 768, 192, 48, 12 C. 256, 128, 32, 8 C\u00e2u 29. Ng\u00e0y \u0111\u1ea7u ti\u00ean, Minh \u0111\u1ee9ng t\u1ea5n \u0111\u01b0\u1ee3c 2 ph\u00fat. Ng\u00e0y th\u1ee9 hai, Minh \u0111\u1ee9ng t\u1ea5n 3 ph\u00fat. S\u1ed1 ph\u00fat \u0111\u1ee9ng t\u1ea5n ng\u00e0y th\u1ee9 ba b\u1eb1ng t\u1ed5ng th\u1eddi gian \u0111\u1ee9ng t\u1ea5n c\u1ee7a ng\u00e0y \u0111\u1ea7u v\u00e0 ng\u00e0y th\u1ee9 hai. Th\u1eddi gian \u0111\u1ee9ng t\u1ea5n ng\u00e0y th\u1ee9 t\u01b0 b\u1eb1ng t\u1ed5ng s\u1ed1 ph\u00fat b\u1ea1n \u1ea5y \u0111\u1ee9ng t\u1ea5n trong ng\u00e0y hai v\u00e0 ng\u00e0y ba. Ng\u00e0y th\u1ee9 m\u1ea5y th\u00ec Minh \u0111\u1ee9ng t\u1ea5n \u0111\u01b0\u1ee3c 55 ph\u00fat? C\u00e2u 30. N\u0103m nay Mary 7 tu\u1ed5i, khi Mary b\u1eb1ng tu\u1ed5i m\u1eb9 b\u00e2y gi\u1edd th\u00ec m\u1eb9 55 tu\u1ed5i. H\u1ecfi n\u0103m nay m\u1eb9 Mary bao nhi\u00eau tu\u1ed5i? 90","\u0110\u00e1p \u00e1n ch\u1ee7 \u0111\u1ec1 5 1B 6A 11A 16B 21D 26C 2B 7B 12D 17B 22B 27A 3C 8B 13D 18B 23C 28B 4A 9A 14A 19A 24B 29B 5C 10A 15B 20D 25B 30A T\u1ea3i App Hoc247 Kids \u0111\u1ec3 xem video h\u01b0\u1edbng d\u1eabn gi\u1ea3i chi ti\u1ebft nh\u00e9! 91","CH\u1ee6 \u0110\u1ec0 6: TH\u1ee6 THU\u1eacT C\u1ed8NG TR\u1eea NH\u00c2N CHIA. LOGIC. QU\u00c3NG \u0110\u01af\u1edcNG. Ki\u1ebfn th\u1ee9c c\u1ea7n nh\u1edb C\u1ed9ng, tr\u1eeb, nh\u00e2n, chia T\u00ednh nh\u1ea9m ph\u00e9p c\u1ed9ng \u2022 Khi c\u1ed9ng hai s\u1ed1, c\u00e1c b\u1ea1n n\u00ean \u0111\u1eb7t s\u1ed1 l\u1edbn tr\u01b0\u1edbc s\u1ed1 nh\u1ecf r\u1ed3i m\u1edbi t\u00ednh nh\u1ea9m \u0111\u1ebfm l\u00ean trong \u0111\u1ea7u s\u1ebd gi\u00fap c\u00e1c b\u1ea1n nh\u1ea9m c\u1ed9ng nhanh h\u01a1n. \u2022 T\u00e1ch s\u1ed1 c\u1ea7n c\u1ed9ng th\u00e0nh t\u1eebng kho\u1ea3ng 10 , 100 ... \u0111\u01a1n v\u1ecb m\u1ed9t l\u1ea7n t\u01b0\u01a1ng \u1ee9ng. \u2022 T\u00e1ch s\u1ed1 c\u1ed9ng th\u1ee9 2 ra \u0111\u1ec3 tr\u00f2n ch\u1ee5c v\u1edbi s\u1ed1 c\u1ed9ng th\u1ee9 1 sau \u0111\u00f3 c\u1ed9ng nh\u1ea9m v\u1edbi ph\u1ea7n c\u00f2n l\u1ea1i. \u2022 D\u00f9ng s\u1ed1 tr\u00f2n ch\u1ee5c g\u1ea7n v\u1edbi s\u1ed1 c\u1ed9ng th\u1ee9 2, ti\u1ebfp theo c\u1ed9ng v\u1edbi s\u1ed1 c\u1ed9ng th\u1ee9 1, sau \u0111\u00f3 tr\u1eeb \u0111i s\u1ed1 th\u1eeba. \u2022T\u00e1ch c\u00e1c s\u1ed1 c\u1ed9ng th\u00e0nh c\u00e1c s\u1ed1 tr\u00f2n ch\u1ee5c r\u1ed3i c\u1ed9ng ri\u00eang s\u1ed1 l\u1ebb c\u1ee7a c\u00e1c s\u1ed1 c\u1ed9ng. V\u00ed d\u1ee5: T\u00ednh nhanh: 349 + 602 + 651 + 398 349 + 602 + 651 + 398 = (346 + 651 ) + (602 + 398) = 1000 + 1000 = 2000 92","T\u00ednh nh\u1ea9m ph\u00e9p tr\u1eeb \u2022 T\u00e1ch s\u1ed1 ra cho tr\u00f2n ch\u1ee5c r\u1ed3i tr\u1eeb ho\u1eb7c c\u1ed9ng s\u1ed1 th\u1eeba. \u2022 T\u00e1ch s\u1ed1 ra cho tr\u00f2n ch\u1ee5c r\u1ed3i tr\u1eeb ho\u1eb7c c\u1ed9ng s\u1ed1 th\u1eeba V\u00ed d\u1ee5: T\u00ednh nhanh: 3145 - 246 + 2347 - 145 + 4246 - 347 3145 - 246 + 2347 - 145 + 4246 - 347 = (3145 - 145) + (4246 - 246) + (2347 - 347) = 3000 + 4000 + 2000 = 7000 + 2000 = 9000 T\u00ednh nh\u1ea9m ph\u00e9p nh\u00e2n \u2022 V\u1eadn d\u1ee5ng t\u00ednh ch\u1ea5t: m\u1ed9t s\u1ed1 nh\u00e2n v\u1edbi m\u1ed9t t\u1ed5ng, m\u1ed9t s\u1ed1 nh\u00e2n v\u1edbi m\u1ed9t hi\u1ec7u, m\u1ed9t t\u1ed5ng chia cho m\u1ed9t s\u1ed1\u2026. + M\u1ed9t s\u1ed1 nh\u00e2n v\u1edbi m\u1ed9t t\u1ed5ng: a x (b + c) = a x b + a x c a x b + a x c = a x (b + c) + M\u1ed9t s\u1ed1 nh\u00e2n v\u1edbi m\u1ed9t hi\u1ec7u: a x (b - c) = a x b - a x c a x b - a x c = a x (b - c) + M\u1ed9t t\u1ed5ng chia cho m\u1ed9t s\u1ed1: (a + b + c) : d = a : d + b : d + c : d a : d + b : d + c : d = (a + b + c) : d V\u00ed d\u1ee5: T\u00ednh nhanh 19 x 82 + 18 x 19 15 : 3 + 45 : 3 + 27 : 3 = 19 x (82 + 18) = (15 + 45 + 27) : 3 = 19 x 100 = 87 : 3 = 1900 = 29 93","T\u00ednh nh\u1ea9m ph\u00e9p chia \u2022 V\u1eadn d\u1ee5ng t\u00ednh ch\u1ea5t: chia m\u1ed9t t\u1ed5ng cho m\u1ed9t s\u1ed1; chia m\u1ed9t hi\u1ec7u cho m\u1ed9t s\u1ed1; chia m\u1ed9t s\u1ed1 cho m\u1ed9t t\u00edch; chia m\u1ed9t t\u00edch cho m\u1ed9t s\u1ed1; + Chia m\u1ed9t t\u1ed5ng cho m\u1ed9t s\u1ed1: (a + b) : c = a : c + b : c + Chia m\u1ed9t hi\u1ec7u cho m\u1ed9t s\u1ed1: (a \u2013 b) : c = a : c \u2013 b : c + Chia m\u1ed9t s\u1ed1 cho m\u1ed9t t\u00edch: a : (b x c) = a : b : c = a : c : b + Chia m\u1ed9t t\u00edch cho m\u1ed9t s\u1ed1: (a x b) : c = a : c x b = b : c x a + Chia cho s\u1ed1 1: a : 1 = a V\u00ed d\u1ee5: T\u00ednh nhanh: (25 x 36) : 9 (25 x 36) : 9 = 25 x (36 : 9) = 25 x 4 = 100 To\u00e1n logic V\u00ed d\u1ee5: T\u00ecm gi\u00e1 tr\u1ecb c\u1ee7a c\u00e1c \u0111\u1ed3 v\u1eadt sau: 94","B\u00e0i gi\u1ea3i To\u00e1n \u0111\u1ebfm V\u00ed d\u1ee5: C\u00f3 bao nhi\u00eau \u0111o\u1ea1n th\u1eb3ng trong h\u00ecnh v\u1ebd sau: B\u00e0i gi\u1ea3i V\u1eady 6 + 3 + 2 = 12 (\u0111o\u1ea1n th\u1eb3ng) 95","B\u00e0i to\u00e1n qu\u00e3ng \u0111\u01b0\u1eddng V\u00ed d\u1ee5: M\u1ed9t xe m\u00e1y \u0111i t\u1eeb A l\u00fac 8 gi\u1edd v\u1edbi v\u1eadn t\u1ed1c 42 km\/gi\u1edd \u0111\u1ebfn B l\u00fac 11 gi\u1edd. T\u00ednh \u0111\u1ed9 d\u00e0i c\u1ee7a qu\u00e3ng \u0111\u01b0\u1eddng AB. B\u00e0i gi\u1ea3i Th\u1eddi gian ng\u01b0\u1eddi \u0111\u00f3 \u0111i l\u00e0: 11 gi\u1edd - 8 gi\u1edd = 3 gi\u1edd \u0110\u1ed9 d\u00e0i qu\u00e3ng \u0111\u01b0\u1eddng AB l\u00e0: 3 x 42 = 126 (km) \u0110\u00e1p s\u1ed1: 126km 96","LUY\u1ec6N T\u1eacP C\u00e2u 1: T\u00ednh nhanh: 300 \u2013 45 \u2013 55 C\u00e2u 2: T\u00ednh nhanh: 240 \u2013 69 \u2013 82 \u2013 31 \u2013 18 C\u00e2u 3: T\u00ednh nhanh: C\u00e2u 4: C\u00f4ng th\u1ee9c n\u00e0o d\u01b0\u1edbi \u0111\u00e2y vi\u1ebft \u0111\u00fang? 97","C\u00e2u 5: M\u1ed9t ng\u01b0\u1eddi \u0111i xe \u0111\u1ea1p trong 3 gi\u1edd v\u1edbi v\u1eadn t\u1ed1c 15 km\/gi\u1edd. T\u00ednh qu\u00e3ng \u0111\u01b0\u1eddng \u0111i \u0111\u01b0\u1ee3c c\u1ee7a ng\u01b0\u1eddi \u0111i xe \u0111\u1ea1p. C\u00e2u 6: M\u1ed9t xe m\u00e1y \u0111i t\u1eeb A l\u00fac 8 gi\u1edd v\u1edbi v\u1eadn t\u1ed1c 42 km\/gi\u1edd \u0111\u1ebfn B l\u00fac 11 gi\u1edd. T\u00ednh \u0111\u1ed9 d\u00e0i c\u1ee7a qu\u00e3ng \u0111\u01b0\u1eddng AB. C\u00e2u 7: C\u00f3 bao nhi\u00eau \u0111o\u1ea1n th\u1eb3ng trong h\u00ecnh d\u01b0\u1edbi \u0111\u00e2y? 98","1001 B\u00c0I TO\u00c1N T\u01af DUY C\u00e2u 8. C\u00f3 bao nhi\u00eau h\u00ecnh tam gi\u00e1c trong h\u00ecnh sau? C\u00e2u 9. C\u00f3 bao nhi\u00eau h\u00ecnh tam gi\u00e1c trong h\u00ecnh sau? C\u00e2u 10. C\u00f3 bao nhi\u00eau h\u00ecnh tam gi\u00e1c trong h\u00ecnh sau? 99","1001 B\u00c0I TO\u00c1N T\u01af DUY C\u00e2u 11. C\u00f3 bao nhi\u00eau h\u00ecnh tam gi\u00e1c trong h\u00ecnh sau? C\u00e2u 12. C\u00f3 bao nhi\u00eau h\u00ecnh tam gi\u00e1c trong h\u00ecnh sau? C\u00e2u 13. C\u00f3 bao nhi\u00eau h\u00ecnh vu\u00f4ng trong h\u00ecnh sau? 100"]