333*6.66+999*7.78怎么巧算
问题描述:
333*6.66+999*7.78怎么巧算
答
333*6.66+999*7.78
=333*3*2.22+999*7.78
=999*2.22+999*7.78
=999*(2.22+7.78)
=999*10
=9990