问题描述：
详细过程，数别变，比如把1/6变成1/2，不行不行
最佳答案： 解法一：
1/6+1/12+1/20+1/30+1/42
=1/(2x3)+1/(3x4)+1/(4x5)+1/(5x6)+1/(6x7)
=(1/2-1/3)+(1/3-1/4)+……+(1/6-1/7)
=1/2-1/7
=5/14
解法二：
1/6+1/12+1/20+1/30+1/42
=(1/6+1/12)+(1/20+1/30)+1/42
=1/4+1/12+1/42
=1/3+1/42
=5/14
