Question

用简便方法计算：99x78

Answer 1

简便方法如下：
99x78
=（100-1）×78
=100×78-1×78
=7800-78
=7722
遇到这种类型的题，首先想到的就是凑整法，只要将其中一个数凑成10的倍数，那么就很好计算了。

Answer 2

用简便方法计算
3.78x9.9
=3.78×（10-0.1）
=3.78×10-3.78×0.1
=37.8-0.378
=37.422

Answer 3

78x9.9
=78x(10-0.1)
=78x10-7.8
=780-7.8
=772.2
祝天天向上。

Answer 4

3.78*9.9
=3.78*9.9+3.78*0.1-3.78*0.1
=3.78*（9.9+0.1）-3.78*0.1
=3:78*10-3.78*0.1
=37.8-0.378
=37.422

Answer 5

99X78=7122
=（99+1）X78-78
=100x78-78
7800-78
=7722