题目内容
计算下面各题,怎样简便就怎样算.
(1)(709-4832÷16)×12
(2)98.3-3.32-5.68+11.7
(3)0.25×3.2×1.25
(4)
÷[(
+
)×
]
(5)(
-
)×5×8.
解:(1)(709-4832÷16)×12,
=(709-302)×12,
=407×12,
=4884;
(2)98.3-3.32-5.68+11.7,
=(98.3+11.7)-(3.32+5.68),
=110-9,
=101;
(3)0.25×3.2×1.25,
=(0.25×4)×(0.8×1.25),
=1×1,
=1;
(4)
÷[(
+
)×
],
=
÷[
×
],
=
÷
,
=
×15,
=5;
(5)(
-
)×5×8,
=
×5×8-
×5×8,
=8-5,
=3.
分析:(1)先算括号内的除法,再算括号内的减法,最后算括号外的乘法;
(2)运用加法交换律与结合率以及减法的性质简算;
(3)把3.2看作4×0.8,运用乘法结合律简算;
(4)先算小括号内的,再算中括号内的,最后算括号外的;
(5)运用乘法分配律简算.
点评:此题考查了分数的四则混合运算,注意运算顺序和运算法则,灵活运用所学的运算定律简便计算.
=(709-302)×12,
=407×12,
=4884;
(2)98.3-3.32-5.68+11.7,
=(98.3+11.7)-(3.32+5.68),
=110-9,
=101;
(3)0.25×3.2×1.25,
=(0.25×4)×(0.8×1.25),
=1×1,
=1;
(4)
![](http://thumb.1010pic.com/pic5/latex/8.png)
![](http://thumb.1010pic.com/pic5/latex/168.png)
![](http://thumb.1010pic.com/pic5/latex/36.png)
![](http://thumb.1010pic.com/pic5/latex/848.png)
=
![](http://thumb.1010pic.com/pic5/latex/8.png)
![](http://thumb.1010pic.com/pic5/latex/60986.png)
![](http://thumb.1010pic.com/pic5/latex/848.png)
=
![](http://thumb.1010pic.com/pic5/latex/8.png)
![](http://thumb.1010pic.com/pic5/latex/2132.png)
=
![](http://thumb.1010pic.com/pic5/latex/8.png)
=5;
(5)(
![](http://thumb.1010pic.com/pic5/latex/36.png)
![](http://thumb.1010pic.com/pic5/latex/112.png)
=
![](http://thumb.1010pic.com/pic5/latex/36.png)
![](http://thumb.1010pic.com/pic5/latex/112.png)
=8-5,
=3.
分析:(1)先算括号内的除法,再算括号内的减法,最后算括号外的乘法;
(2)运用加法交换律与结合率以及减法的性质简算;
(3)把3.2看作4×0.8,运用乘法结合律简算;
(4)先算小括号内的,再算中括号内的,最后算括号外的;
(5)运用乘法分配律简算.
点评:此题考查了分数的四则混合运算,注意运算顺序和运算法则,灵活运用所学的运算定律简便计算.
![](http://thumb2018.1010pic.com/images/loading.gif)
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