题目内容
(![]() ![]() ![]() ![]() | 125×0.25×3.2 | ![]() |
![]() | 5025-2940÷28×37 | (25+25+25)×![]() |
解:(1)(
-
)×(
+
),
=
×
,
=
;
(2)125×0.25×3.2
=125×0.25×4×0.8,
=(125×0.8)×(0.25×4),
=100×1,
=100;
(3)
+(
)×
,
=
+
×
,
=
+
,
=
;
(4)
×
+
÷8,
=
×
+
×
,
=(
)×
,
=
×
,
=
;
(5)5025-2940÷28×37,
=5025-105×37,
=5025-3885,
=1140;
(6)(25+25+25)×![](http://thumb.1010pic.com/pic5/latex/8.png)
=25×3×
,
=25.
分析:(2)可将3.2拆分为4×0.8后再据乘法结合律进行简便计算;
(4)可用乘法分配律进行简便计算;
(6)可据整数乘法的意义将25+25+25改成乘法算式25×3进行计算;
其余算式根据四则混合运算顺序进行计算即可.
点评:完成此类题目要注意分析式中数据的特点及内在联系,看是否能够利用简便方法进行计算.
![](http://thumb.1010pic.com/pic5/latex/365.png)
![](http://thumb.1010pic.com/pic5/latex/1302.png)
![](http://thumb.1010pic.com/pic5/latex/3982.png)
![](http://thumb.1010pic.com/pic5/latex/8.png)
=
![](http://thumb.1010pic.com/pic5/latex/2235.png)
![](http://thumb.1010pic.com/pic5/latex/4442.png)
=
![](http://thumb.1010pic.com/pic5/latex/2520.png)
(2)125×0.25×3.2
=125×0.25×4×0.8,
=(125×0.8)×(0.25×4),
=100×1,
=100;
(3)
![](http://thumb.1010pic.com/pic5/latex/168.png)
![](http://thumb.1010pic.com/pic5/latex/215170.png)
![](http://thumb.1010pic.com/pic5/latex/4458.png)
=
![](http://thumb.1010pic.com/pic5/latex/168.png)
![](http://thumb.1010pic.com/pic5/latex/5193.png)
![](http://thumb.1010pic.com/pic5/latex/4458.png)
=
![](http://thumb.1010pic.com/pic5/latex/168.png)
![](http://thumb.1010pic.com/pic5/latex/36.png)
=
![](http://thumb.1010pic.com/pic5/latex/60986.png)
(4)
![](http://thumb.1010pic.com/pic5/latex/597.png)
![](http://thumb.1010pic.com/pic5/latex/9777.png)
![](http://thumb.1010pic.com/pic5/latex/9777.png)
=
![](http://thumb.1010pic.com/pic5/latex/597.png)
![](http://thumb.1010pic.com/pic5/latex/9777.png)
![](http://thumb.1010pic.com/pic5/latex/9777.png)
![](http://thumb.1010pic.com/pic5/latex/112.png)
=(
![](http://thumb.1010pic.com/pic5/latex/205407.png)
![](http://thumb.1010pic.com/pic5/latex/9777.png)
=
![](http://thumb.1010pic.com/pic5/latex/13.png)
![](http://thumb.1010pic.com/pic5/latex/9777.png)
=
![](http://thumb.1010pic.com/pic5/latex/1154.png)
(5)5025-2940÷28×37,
=5025-105×37,
=5025-3885,
=1140;
(6)(25+25+25)×
![](http://thumb.1010pic.com/pic5/latex/8.png)
=25×3×
![](http://thumb.1010pic.com/pic5/latex/8.png)
=25.
分析:(2)可将3.2拆分为4×0.8后再据乘法结合律进行简便计算;
(4)可用乘法分配律进行简便计算;
(6)可据整数乘法的意义将25+25+25改成乘法算式25×3进行计算;
其余算式根据四则混合运算顺序进行计算即可.
点评:完成此类题目要注意分析式中数据的特点及内在联系,看是否能够利用简便方法进行计算.
![](http://thumb2018.1010pic.com/images/loading.gif)
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