问题 解答题
脱式计算
32×0.16×2.5×1.25
6.4×4.2-4.2×
2
5

(0.3+
1
5
)×1.6-
4
5

9÷[1-(
2
5
+
9
20
)].
答案

(1)32×0.16×2.5×1.25,

=8×4×0.16×2.5×1.25,

=(8×1.25)×(4×2.5)×0.16,

=10×10×0.16,

=100×0.16,

=16;

(2)6.4×4.2-4.2×

2
5

=4.2×(6.4-0.4),

=4.2×6,

=25.2;

(3)(0.3+

1
5
)×1.6-
4
5

=0.5×1.6-0.8,

=0.8-0.8,

=0;

(4)9÷[1-(

2
5
+
9
20
)],

=9÷[1-

17
20
],

=9÷

3
20

=60.

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