灵活计算下面各题.(1)4.87×1.25×0.8(2)(5.6-5.6×0.7)÷22.4(3)3.7×9.9(4)8.56×7.5+8.56×2.5.

发布时间:2020-08-16 01:37:18

灵活计算下面各题. (1)4.87×1.25×0.8(2)(5.6-5.6×0.7)÷22.4(3)3.7×9.9(4)8.56×7.5+8.56×2.5.

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解:(1)4.87×1.25×0.8,
=4.87×(1.25×0.8),
=4.87×1,
=4.87;

(2)(5.6-5.6×0.7)÷22.4,
=(1-0.7)×5.6÷22.4,
=0.3×5.6÷22.4,
=1.68÷22.4,
=0.075;

(3)3.7×9.9,
=3.7×(10-0.1),
=3.7×10-3.7×0.1,
=37-0.37,
=36.63;

(4)8.56×7.5+8.56×2.5,
=8.56×(7.5+2.5),
=8.56×10,
=85.6.
解析分析:(1)运用乘法结合律简算;
(2)括号内运用乘法分配律简算,最后算除法;
(3)把9.9看作10-0.1,运用乘法结合律简算;
(4)运用乘法结合律简算.

点评:完成本题要注意分析式中数据,运用合适的简便方法计算.
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