数学题简算,1/2+1/6+1/12……+1/72+1/90
问题描述:
数学题简算,1/2+1/6+1/12……+1/72+1/90
答
=(1-1/2)+(1/2-1/3)+(1/3-1/4)……+(1/8-1/9)+(1/9-1/10)
=1-1/10
=9/10