你大概写错了,应该是1/2+1/6+1/12+1/20+....+1/(n(n+1))=1/(1*2)+1/(2*3)+1/(3*4)+...+1/(n(n+1)=1/1-1/2+1/2-1/3+1/4-1/5+...+1/n-1/(n+1)=1-1/(n+1)n=100时,1-1/(n+1)=n/(n+1)=100/101
