1/2 - 1/6 - 1/12 - 1/20 - 1/30 - 1/42 - 1/56怎么算

问题描述:

1/2 - 1/6 - 1/12 - 1/20 - 1/30 - 1/42 - 1/56怎么算

原式=1/2-1/2+1/3-1/3+1/4-1/4+1/5-1/5+1/6-1/6+1/7-1/7+1/8=1/2+1/8=1/8