下面各题,怎样简便就怎样算. 1.2×0.5+3.5×1.2
1个回答

解题思路:(1)(2)(6)运用乘法分配律简算.

(3)把101看作100+1,运用乘法分配律简算.

(4)把3.2看作8×0.4,运用乘法结合律简算.

(5)运用除法的性质简算.

(1)1.2×0.5+3.5×1.2

=(0.5+3.5)×1.2

=4×1.2

=4.8

(2)3.5×0.7+5.5×0.7+0.7

=(3.5+5.5+1)×0.7

=10×0.7

=7

(3)6.2×101

=6.2×(100+1)

=6.2×100+6.2

=620+6.2

=626.2

(4)0.125×3.2

=0.125×8×0.4

=(0.125×8)×0.4

=1×0.4

=0.4

(5)21÷0.25÷0.4

=21÷(0.25×0.4)

=21÷0.1

=210

(6)0.83×101-0.83

=0.83×(101-1)

=0.83×100

=83

点评:

本题考点: 小数四则混合运算.

考点点评: 注意观察题目中数字构成的特点和规律,善于灵活运用运算定律或运算技巧,进行简算.