Question

27.5×3.9-75×0.39怎样简便计算？

Answer 1

因为75×0.39=7.5×3.9，所以原式等于27.5×3.9-7.5×3.9，运用乘法分配律逆运算就是有3.9×（27.5-7.5）=3.9×20=78。

Answer 2

27.5×3.9-75×0.39
=27.5×3.9-7.5×3.9
=(27.5-7.5)×3.9
=20×3.9
=78