题目内容
用简便的方法计算.
17
| 2008×
|
(1)17
×
+
×
,
=17
×
+
×
,
=(17
+
)×
,
=18×
,
=15;
(2)2008×
,
=(2009-1)×
,
=2009×
-1×
,
=2008-
,
=2007
.
| 1 |
| 8 |
| 5 |
| 6 |
| 7 |
| 8 |
| 6 |
| 5 |
=17
| 1 |
| 8 |
| 5 |
| 6 |
| 7 |
| 8 |
| 5 |
| 6 |
=(17
| 1 |
| 8 |
| 7 |
| 8 |
| 5 |
| 6 |
=18×
| 5 |
| 6 |
=15;
(2)2008×
| 2008 |
| 2009 |
=(2009-1)×
| 2008 |
| 2009 |
=2009×
| 2008 |
| 2009 |
| 2008 |
| 2009 |
=2008-
| 2008 |
| 2009 |
=2007
| 1 |
| 2009 |
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