1/20+1/30+1/42+1/56+1/72+1/90+1/110+1/132=?
问题描述：
1/20+1/30+1/42+1/56+1/72+1/90+1/110+1/132=?
能不能简便运算?
答
1/20+1/30+1/42+1/56+1/72+1/90+1/110+1/132
=1/4-1/5+1/5-1/6+1/6-1/7+1/7-1/8+……+1/11-1/12
=1/4-1/12
=3/12-1/12
=2/12
=1/6