Question

这几道题怎么做。全部简便算法。谢谢

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Answer 1

2/9-7/16×2/9
=2/9×（1-7/16）
=2/9×9/16
=1/8

追答

2/5×4×3/4
=2/5×（4×3/4）
=2/5×3
=1又1/5

1/2×1/15+1/3×1/2
=1/2×（1/15+1/3）
=1/2×2/5
=1/5

4/5×7/9×5/8
=4/5×5/8×7/9
=1/2×7/9
=7/18

5/7×16×21/5
=5/7×21/5×16
=3×16
=48

5/6×5/9+5/9×1/6
=（5/6+1/6）×5/9
=1×5/9
=5/9

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