举个例子:1/2+1/6+1/12+1/20+1/30
解 原式=1/(1*2)+1/(2*3)+1/(3*4)+1/(4*5)+1/(5*6)
=1-1/2+1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6
=5/6