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乘法的估算

乘法的估算. 沙市北京路三小 孔静 编辑整理. 今天特价： 柚子每个 3 元。假如要买 21 个，大约要花多少元钱？. 21×3. ≈ 60 （ 元）. ___. 20. 答：大约要花 60 元钱。. 小礼堂. 有 350 名同学来参加联欢会，能坐下吗？. 每排有 22 个座位。. 一共有 18 排. 各显神通. 18≈20 22×20=440. 22≈20 18×20=360 所以能坐下。. 18≈20 22≈20 20×20=400. 23x22. 23≈20 20x22=440

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乘法的估算

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  1. 乘法的估算 沙市北京路三小 孔静 编辑整理

  2. 今天特价： 柚子每个3元。假如要买21个，大约要花多少元钱？ 21×3 ≈ 60（元） ___ 20 答：大约要花60元钱。

  3. 小礼堂 有350名同学来参加联欢会，能坐下吗？ 每排有22个座位。 一共有18排

  4. 各显神通 18≈20 22×20=440 22≈20 18×20=360 所以能坐下。 18≈20 22≈20 20×20=400

  5. 23x22 • 23≈20 20x22=440 • 22≈20 23x20=460 • 23≈20 22≈20 20x20=400

  6. 31≈30 30 x20=60（米） • 18≈20 20 x30=60 (米) • 11≈10 一分钟 =60秒 10x60=600(米)

  7. 1 2 3 4 5 6 7 8 9 • 93÷3=31(棵) 31x9 • 31≈30 30x9=270(棵) • 9≈10 31x10=310 (棵) • 31≈30 9≈10 10x30=300(棵) ≈270 (棵)

  8. 积大于2000的算式 48x31 96x53 69x38 29x78 积小于2000的算式 24x67 43x25

  9. 估算: 16  70 6  30 =180 =1120 7  90 30  12 =360 =630 6  70 25  60 =1500 =420 35  20 =700 50  12 =600

  10. 数学书练习十四 第10题 写在练习册上 今天作业

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