题目内容
12.5×0.5×4×0.8 运用 律和 律可以使计算简便，得数是 ．
分析：12.5×0.5×4×0.8=12.5×4×0.5×0.8=（12.5×4）×（0.5×0.8）=20；运用了乘法交换律和乘法结合律，由此解答即可．
解答：解：12.5×0.5×4×0.8
=12.5×4×0.5×0.8
=（12.5×4）×（0.5×0.8）
=50×0.4
=20；
运用了乘法交换律和乘法结合律，得数是20；
故答案为：乘法交换，乘法结合，20．
=12.5×4×0.5×0.8
=（12.5×4）×（0.5×0.8）
=50×0.4
=20；
运用了乘法交换律和乘法结合律，得数是20；
故答案为：乘法交换，乘法结合，20．
点评：在利用运算定律简算时，要细心分析题目数据及运算符号，选择合适的运算定律计算．
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