1/2 1/6 1/12 1/20 1/30 简便计算,
问题描述：
1/2 1/6 1/12 1/20 1/30 简便计算,
中间加号连接
答
1/2+1/6+1/12+1/20+1/30
=1-1/2+1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6
=1-1/6
=5/6