40%× +60%× | 20%× -20%× | ×35%+0.25×65% |
| 75%×125-75%×25 | ( + )×45 | 15×40%+85×40% |
+60%×
,=(40%+60%)×
,=1×
,=
;(2)20%×
-20%×
,=20%×(
-
),=20%×1,
=0.2;
(3)
×35%+0.25×65%,=0.25×(35%+65%),
=0.25×1,
=0.25;
(4)75%×125-75%×25,
=75%×(125-25),
=0.75×100,
=75;
(5)(
+
)×45,=
×45+
×45,=30+27,
=57;
(6)15×40%+85×40%,
=(15+85)×0.4,
=100×0.4,
=40.
分析:这几个题目都可以运用乘法分配律简算.
点评:乘法分配律是最常用的简算方法,要熟记,并灵活运用.