列项
1/1*2=1-1/2
1/2*3=1/2-1/3
.
1/n(n+1)=1/n-1/(n+1)
1/1*2+1/2*3+1/3*4+.+1/n(n+1)
=1-1/2+1/2-1/3+.+1/n-1/(n+1)
=1-1/(n+1)
=n/(n+1)
n=100时
原式=100/101
列项
1/1*2=1-1/2
1/2*3=1/2-1/3
.
1/n(n+1)=1/n-1/(n+1)
1/1*2+1/2*3+1/3*4+.+1/n(n+1)
=1-1/2+1/2-1/3+.+1/n-1/(n+1)
=1-1/(n+1)
=n/(n+1)
n=100时
原式=100/101