题目内容
计算下面的题,能简算的要用简便方法计算哟,并写出简算步骤.
①2.35-81÷27×0.45 ②125×
×0.8×![数学公式](http://thumb.1010pic.com/pic5/latex/2405.png)
③3×(
+
)-
④[1-(
+
)]÷
.
解:①2.35-81÷27×0.45,
=2.35-3×0.45,
=2.35-1.35,
=1;
②125×
×0.8×
,
=(125×0.8)×(
×
),
=100×
,
=50;
③3×(
+
)-
,
=3×
-
,
=
-
,
=
;
④[1-(
+
)]÷
,
=[1-
]×4,
=
×4,
=
.
分析:算式①③④根据四则混合运算的运算顺序计算即可:先算乘除,再算加减,有括号的要先算括号里面的;
算式②可根据乘法交换律及结合律进行计算.
点评:完成有关于分数的计算题目时要细心,关键要注意通分约分.
=2.35-3×0.45,
=2.35-1.35,
=1;
②125×
![](http://thumb.1010pic.com/pic5/latex/1231.png)
![](http://thumb.1010pic.com/pic5/latex/2405.png)
=(125×0.8)×(
![](http://thumb.1010pic.com/pic5/latex/1231.png)
![](http://thumb.1010pic.com/pic5/latex/2405.png)
=100×
![](http://thumb.1010pic.com/pic5/latex/13.png)
=50;
③3×(
![](http://thumb.1010pic.com/pic5/latex/4457.png)
![](http://thumb.1010pic.com/pic5/latex/6.png)
![](http://thumb.1010pic.com/pic5/latex/335.png)
=3×
![](http://thumb.1010pic.com/pic5/latex/3661.png)
![](http://thumb.1010pic.com/pic5/latex/335.png)
=
![](http://thumb.1010pic.com/pic5/latex/28483.png)
![](http://thumb.1010pic.com/pic5/latex/335.png)
=
![](http://thumb.1010pic.com/pic5/latex/96.png)
④[1-(
![](http://thumb.1010pic.com/pic5/latex/96.png)
![](http://thumb.1010pic.com/pic5/latex/597.png)
![](http://thumb.1010pic.com/pic5/latex/96.png)
=[1-
![](http://thumb.1010pic.com/pic5/latex/5192.png)
=
![](http://thumb.1010pic.com/pic5/latex/597.png)
=
![](http://thumb.1010pic.com/pic5/latex/33.png)
分析:算式①③④根据四则混合运算的运算顺序计算即可:先算乘除,再算加减,有括号的要先算括号里面的;
算式②可根据乘法交换律及结合律进行计算.
点评:完成有关于分数的计算题目时要细心,关键要注意通分约分.
![](http://thumb2018.1010pic.com/images/loading.gif)
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