3.83乘以2.17加上2.17乘以7.17减去21.7 巧算

题目

3.83乘以2.17加上2.17乘以7.17减去21.7 巧算
谢谢

答案

3.83*2.17+2.17*7.17-21.7
=2.17*(3.83+7.17)-2.17*10
=2.17*11-2.17*10
=2.17*(11-10)
=2.17