3.9*9.9+0.39=?的简便算法是什麽
问题描述：
3.9*9.9+0.39=?的简便算法是什麽
答
3.9*(9.9+0.1)
答
原式=3.9*0.9+3.9*0.1=3.9*(9.9+0.1)=3.9*10=39
答
3.9*9.9+0.39
=0.39*99+0.39
=0.39*(99+1)
=0.39*100
=39
答
3.9*9.9+0.39=3.9*9.9+3.9*0.1=3.9*10=39
答
3.9×9.9+0.39
= 3.9×9.9+3.9×0.1
= 3.9×（9.9+0.1）
= 3.9×10
= 39
答
3.9*(9.9+11)