分类：电脑/网络-互联网-上网帮助
问题：分数计算1/2+1/6+1/12+1/20+1/30+1/42+ 
1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72+1/90
要写出计算过程 
回答：=(1-1/2)+(1/2-1/3)+(1/3-1/4)+(1/4-1/5)+(1/5-1/6)+(1/6-1/7)+
(1/7-1/8)+(1/8-1/9)+(1/9-1/10)
=1-1/10
=9/10