Question

简便计算39.7x2.8+39.7x7.1？

Answer 1

39.7*2.8+39.7*7.1

=39.7*（2.8+7.1）

=39.7*9.9

=39.7*（10-0.1）

=39.7*10-39.7*0.1

=397-3.97

=393.03

这题的关键是有公因子39.7，后面2.8+7.1=9.9=10-0.1。至少我这样换算不用笔算，直接口算也行。希望这样回答能满意。

Answer 2

39.7x2.8+39.7x7.1=39.7x（2.8+7.1）=39.7x9.9=39.7x10-39.7x0.1=397-3.97=393.03

Answer 3

39.7×2.8+39.7×7.1
=39.7×(2.8+7.1)
=39.7×9.9
=39.7×(10-0.1)
=39.7×10-39.7×0.1
=397-3.97
=393.03

Answer 4

39.7x2.8+39.7x7.1
=39.7x(2.8+7.1)
=39.7x9.9
=39.7x(10-0.1)
=39.7x10-39.7x0.1
=397-3.97
=393.03
这道题的简便算法运用了乘法分配率

Answer 5

39.7x2.8+39.7x7.1
=39.7x(2.8+7.1)
=39.7x9.9
=39.7x(10-0.1)
=39.7x10-39.7x0.1
=397-3.97
=393.03