Question

7.8*9.9+0.78的简便计算该怎么算？

是简便计算，不是递等式计算哦!

Answer 1

0.78=？
0.78=7.8*0.1！！！
然后干嘛？
提取公因式

Answer 2

7.8*9.9+0.78
=7.8*9.9+7.8*0.1
=7.8*(9.9+0.1)
=7.8*10
=78

Answer 3

=7.8*(10-0.1)+0.78
=78-0.78+0.78
=78

Answer 4

7.8*9.9+0.78
=7.8*(10-0.1)+0.78
=78-0.78+0.78
=78

Answer 5

0.78(10*9.9+1)
=0.78(99+1)
=0.78*100
78