Question

1/5+1/25+1/125+1/625+1/3125的简便计算？

Answer 1

根据题意，这道题用到的简便计算方法是扩大分母，合并同类项，原式=625/3125+125/3125+25/3125+5/3125+1/3125=（625+125+25+5+1）/3125=781/3125=781/3125。

Answer 2

这道题的简便方法如下：
设y=1/5+1/25+1/125+1/625+1/3125
两边都乘以1/5得
1/5y=1/25+1/125+……+1/3125+1/15625
两式相减，错位消去中间项得
4/5y=1/5-1/15625
解得y=781/3125
所以原式=781/3125

Answer 3

这些分数的分母都是5的倍数，它的公分母为3125，原式=625/3125+125/3125+25/3125+1/3125=625/3125+150/3125+1/3125=775/3125+1/3125=776/3125。

Answer 4

=1/4-1/15625*5/4
=781/3125
=0.24992

Answer 5

1/5+1/25+1/125+1/625+1/3125
=（625+125+25+5+1）/3125
=781/3125