(1)6.43+2.58-6.43+2.58(2)6.6*9.8

问题描述:

(1)6.43+2.58-6.43+2.58
(2)6.6*9.8

5.16
64.68

(1)6.43+2.58-6.43+2.58
=(6.43-6.43)+(2.58+2.58)
=0+5.16
=5.16
(2)6.6*9.8
=6.6×(10-0.2)
=66-6.6×0.2
=66-1.32
=64.68

6.43+2.58-6.43+2.58
=6.43-6.43+2.58+2.58
=5.16
6.6*9.8
=6.6*10-6.6*0.2
=66-1.32
=64.68