5
怎么简便就怎么算
$576 - 133 - 67 =$ $394 - 94 - 26 - 74 =$
$900 - 298 - 2 =$ $(156 + 274) + 126 =$
$1074 - 287 - 113 =$ $655 - 190 - 155 =$
$345 - 77 - 23 =$ $(283 + 149) + 51 =$
$1025 - 237 - 763 =$ $94 + 38 + 106 =$
$520 - 165 - 35 =$ $357 - 157 - 2 =$
$868 - 77 - 223 =$ $(23 + 48) + 52 =$
$234 - 34 - 50 =$ $304 - 167 - 33 =$
$438 - 74 - 38 =$ $(29 + 37) + 71 =$
$460 - 138 - 62 =$ $937 - 137 - 59 =$
$119 + (81 + 264) =$ $132 - 50 - 25 - 25 =$
$1000 - 488 - 10 - 2 =$
$8 + 9 + 10 + 11 + 12 + 13 = ($$) × ($$) = ($$)$
$1 + 2 + 3 + ··· + 18 + 19 + 20 = ($$) × ($$) = ($$)$
$1 + 3 + 5 + ··· + 15 + 17 + 19 = ($$) × ($$) = ($$)$
$2 + 4 + 6 + ··· + 16 + 18 + 20 = ($$) × ($$) = ($$)$
$1 + 3 + 5 + 7 + ··· + 95 + 97 + 99 = ($$) × ($$) = ($$)$
$260 - 1 - 2 - 3 - 4 - ··· - 19 - 20 = 260 - ($$) × ($$)$
$= ($$)$
时间（）

1. $576 - 133 - 67 = 576 - (133 + 67) = 576 - 200 = 376$
2. $394 - 94 - 26 - 74 = (394 - 94) - (26 + 74) = 300 - 100 = 200$
3. $900 - 298 - 2 = 900 - (298 + 2) = 900 - 300 = 600$
4. $(156 + 274) + 126 = 156 + (274 + 126) = 156 + 400 = 556$
5. $1074 - 287 - 113 = 1074 - (287 + 113) = 1074 - 400 = 674$
6. $655 - 190 - 155 = (655 - 155) - 190 = 500 - 190 = 310$
7. $345 - 77 - 23 = 345 - (77 + 23) = 345 - 100 = 245$
8. $(283 + 149) + 51 = 283 + (149 + 51) = 283 + 200 = 483$
9. $1025 - 237 - 763 = 1025 - (237 + 763) = 1025 - 1000 = 25$
10. $94 + 38 + 106 = (94 + 106) + 38 = 200 + 38 = 238$
11. $520 - 165 - 35 = 520 - (165 + 35) = 520 - 200 = 320$
12. $357 - 157 - 2 = (357 - 157) - 2 = 200 - 2 = 198$
13. $868 - 77 - 223 = 868 - (77 + 223) = 868 - 300 = 568$
14. $(23 + 48) + 52 = 23 + (48 + 52) = 23 + 100 = 123$
15. $234 - 34 - 50 = (234 - 34) - 50 = 200 - 50 = 150$
16. $304 - 167 - 33 = 304 - (167 + 33) = 304 - 200 = 104$
17. $438 - 74 - 38 = (438 - 38) - 74 = 400 - 74 = 326 - 0=326$
18. $(29 + 37) + 71 = (29 + 71) + 37 = 100 + 37 = 137$
19. $460 - 138 - 62 = 460 - (138 + 62) = 460 - 200 = 260$
20. $937 - 137 - 59 = (937 - 137) - 59 = 800 - 59 = 741$
21. $119 + (81 + 264) = (119 + 81) + 264 = 200 + 264 = 464$
22. $132 - 50 - 25 - 25 = 132 - (50 + 25 + 25) = 132 - 100 = 32$
23. $1000 - 488 - 10 - 2 = 1000 - (488 + 10 + 2) = 1000 - 500 = 500$
24. $8 + 9 + 10 + 11 + 12 + 13 = (8 + 13) × 3 = 21 × 3 = 63/ (10+11)× 3/2-9（调整）= 63$（首尾相加法，共6个数，中间两个数为10.5的平均值，实际用整数为（8+13）*3=63） 简化为：$ (21) × (3) = (63)$
25. $1 + 2 + 3 + ··· + 18 + 19 + 20 = (1 + 20) × 10 = 21 × 10 = 210/2*20=210$（等差数列求和） $ (21) × (10) = (210)$
26. $1 + 3 + 5 + ··· + 15 + 17 + 19 = (1 + 19) × 5 = 20 × 5 = 100/2*10=100$（等差数列求和）$ (20) × (5) = (100)$
27. $2 + 4 + 6 + ··· + 16 + 18 + 20 = (2 + 20) × 5 = 22 × 5 = 110/2*10=110$（等差数列求和） $ (11× 2) × 5/2 的整数倍= (22中2和11取11为代表) × (5) = (110)$ 简化为 $ (11 × 2) × (5) = (110)$ 或 $ (22/2 × 10) = (110)$
28. $1 + 3 + 5 + 7 + ··· + 95 + 97 + 99 = (1 + 99) × 25 = 100 × 25 = 2500/2=25 × 100/2=2500$（等差数列求和） $ (100) × (25/2的整数倍，即实际为项数25) = (2500)$ 简化为 $ (50 × 2) × 25/2 = (2500)$ 或 $100 × 25 / 2 × 2/2 = 2500$，最终 $ (100) × (25 ÷ 2 × 1（即项数的一半乘2实际不用除）) = 2500$ 简写为 $ (100 × 25) ÷ 2 × 1 = 2500$ 或直接 $25 × 100 = 2500$
29. $260 - 1 - 2 - 3 - 4 - ··· - 19 - 20 = 260 - (1 + 20) × 10 = 260 - 210 = 50$
$260 - (21 × 10 - 0（因为1到20和为210）) = 260 - 210 = 50$ 简化为 $260 - (21 × 10) = 50$
$ = (50)$
时间（根据题目量，假设为15分钟或其他合理时间）