题目内容
用两种方法简算:26×
+
.
| 12 |
| 25 |
| 13 |
| 25 |
考点:分数的简便计算
专题:运算定律及简算
分析:方法一:先把25分解成25+1,再运用乘法分配律以及加法结合律简算;
方法二:把
化成1-
,再运用两次乘法分配律简算.
方法二:把
| 12 |
| 25 |
| 13 |
| 25 |
解答:
解:方法一:
26×
+
=(25+1)×
+
=25×
+1×
+
=12+(
+
)
=12+1
=13;
方法二:
26×
+
=26×(1-
)+
=26×1-26×
+
=26-(26-1)×
=26-25×
=26-13
=13.
26×
| 12 |
| 25 |
| 13 |
| 25 |
=(25+1)×
| 12 |
| 25 |
| 13 |
| 25 |
=25×
| 12 |
| 25 |
| 12 |
| 25 |
| 13 |
| 25 |
=12+(
| 12 |
| 25 |
| 13 |
| 25 |
=12+1
=13;
方法二:
26×
| 12 |
| 25 |
| 13 |
| 25 |
=26×(1-
| 13 |
| 25 |
| 13 |
| 25 |
=26×1-26×
| 13 |
| 25 |
| 13 |
| 25 |
=26-(26-1)×
| 13 |
| 25 |
=26-25×
| 13 |
| 25 |
=26-13
=13.
点评:完成本题要注意分析式中数据,开拓思路,运用合适的简便方法计算.
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