1又1/2-1/12-1/20-1/30-1/42

问题描述:

1又1/2-1/12-1/20-1/30-1/42

要答案还是要简便算法呀?

1又1/2-1/2+1/3-1/3+1/4-1/5+1/5-1/6+1/6-1/7
1-1/7
=6/7