1/1*2+1/2*3+1/3*4+1/4*5+1/5*6+1/6*7+```+1/29*30

问题描述:

1/1*2+1/2*3+1/3*4+1/4*5+1/5*6+1/6*7+```+1/29*30

1/1*2+1/2*3+1/3*4+1/4*5+1/5*6+1/6*7+```+1/29*30
=1-1/2+1/2-1/3+.+1/29-1/30
=1-1/30
=29/30