1/2+1/6+1/12+1/20(简算)
问题描述:
1/2+1/6+1/12+1/20(简算)
答
1/2+1/6+1/12+1/20
=1/2+1/2-1/3+1/3-1/4+1/4-1/5
=1-1/5
=4/5