题目内容
用自己喜欢的方法计算.
(1)
÷7+
×
(2)(
+
)×7×5
(3)2010×
.
(1)
| 8 |
| 13 |
| 1 |
| 7 |
| 5 |
| 13 |
(2)(
| 6 |
| 7 |
| 4 |
| 5 |
(3)2010×
| 2010 |
| 2011 |
分析:算式(1)(2)可据乘法分配律进行简便计算;
算式(3)可将根据乘法分配律将原式变为:2010×(1-
)进行简便计算.
算式(3)可将根据乘法分配律将原式变为:2010×(1-
| 1 |
| 2011 |
解答:解:(1)
÷7+
×
=
×
+
×
,
=(
+
)×
,
=1×
,
=
;
(2)(
+
)×7×5
=(
+
)×7×5,
=
×7×5+
×7×5,
=30+28,
=58;
(3)2010×
=2010×(1-
),
=2010-2010×
,
=2010-
,
=2009
.
| 8 |
| 13 |
| 1 |
| 7 |
| 5 |
| 13 |
=
| 8 |
| 13 |
| 1 |
| 7 |
| 1 |
| 7 |
| 5 |
| 13 |
=(
| 8 |
| 13 |
| 5 |
| 13 |
| 1 |
| 7 |
=1×
| 1 |
| 7 |
=
| 1 |
| 7 |
(2)(
| 6 |
| 7 |
| 4 |
| 5 |
=(
| 6 |
| 7 |
| 4 |
| 5 |
=
| 6 |
| 7 |
| 4 |
| 5 |
=30+28,
=58;
(3)2010×
| 2010 |
| 2011 |
=2010×(1-
| 1 |
| 2011 |
=2010-2010×
| 1 |
| 2011 |
=2010-
| 2010 |
| 2011 |
=2009
| 1 |
| 2011 |
点评:算式(3)也可以将原式变为(2011-1)×
进行简便计算.
| 2010 |
| 2011 |
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