39乘27加39怎样简算
问题描述：
39乘27加39怎样简算
答
39 X 27 + 39
= 39 X ( 27 + 1 )
= 39 X 28
= ( 40 - 1) X 28
= 40 X 28 - 28
= 40 X ( 30 - 2) - 28
= 40 X 30 - 40 X 2 - 28
= 1200 - 80 28
= 1120 - 28
= 1092