简便计算 4道,

题目

简便计算 4道,
10.4-9.6×0.5
3.12+3.12×99
0.45×7.5-0.45×6.5
（4.23+6.17）×0.8

答案

10.4-9.6×0.5
=10.4-4.8
=5.6
3.12+3.12×99
=3.12(1+99)
=312
0.45×7.5-0.45×6.5
=0.45(7.5-6.5)
=0.45
（4.23+6.17）×0.8
=10.4×0.8
=8.32