巧算:1/2+1/6+1/12+1/20+1/30+1/42+1/56=?
问题描述:
巧算:1/2+1/6+1/12+1/20+1/30+1/42+1/56=?
答
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=7/8
巧算:1/2+1/6+1/12+1/20+1/30+1/42+1/56=?
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=7/8