Question

3.09x3.9÷3.09x3.9的简便方法？

Answer 1

简便计算为
3.09*3.9÷3.09*3.9
=3.09÷3.09*（3.9*3.9）
=1*15.21
=15.21

Answer 2

3.09×3.9÷3.09×3.9
=（3.09÷3.09）×3.9×3.9
=1×3.9×3.9
=3.9×4-3.9×0.1
=15.6-0.39
=15.21