解:(1)
![](http://thumb.1010pic.com/pic5/latex/204581.png)
,
=(2-
![](http://thumb.1010pic.com/pic5/latex/254276.png)
)×
![](http://thumb.1010pic.com/pic5/latex/518580.png)
,
=2×
![](http://thumb.1010pic.com/pic5/latex/518580.png)
,
=
![](http://thumb.1010pic.com/pic5/latex/518581.png)
,
=80;
(2)
![](http://thumb.1010pic.com/pic5/latex/204582.png)
,
=
![](http://thumb.1010pic.com/pic5/latex/518582.png)
,
=
![](http://thumb.1010pic.com/pic5/latex/518583.png)
;
(3)
![](http://thumb.1010pic.com/pic5/latex/204583.png)
,
=(2003+1)×
![](http://thumb.1010pic.com/pic5/latex/28270.png)
,
=2003×
![](http://thumb.1010pic.com/pic5/latex/28270.png)
+1×
![](http://thumb.1010pic.com/pic5/latex/28270.png)
,
=2002+
![](http://thumb.1010pic.com/pic5/latex/28270.png)
,
=2002
![](http://thumb.1010pic.com/pic5/latex/28270.png)
.
分析:(1)化12.5%=
![](http://thumb.1010pic.com/pic5/latex/112.png)
,先运用加法结合律计算
![](http://thumb.1010pic.com/pic5/latex/274123.png)
,再依据四则运算计算方法,先算第二级运算,再算第一级运算,如果只含有同一级运算,按照从左到右顺序计算,有括号先算括号里面的解答,
(2)先同时计算乘法,再算加法解答,
(3)化2004=2003+1,再运用乘法分配律求解.
点评:解答此类题目的关键是依据各数的特点选择并运用正确的简便算法解决问题.