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问题: 求和

1/2*3+1/3*4+1/4*5+1/5*6+……+1/99*100

解答:

1/[n(n+1)]=1/n-1/(n+1)

1/2*3+1/3*4+1/4*5+1/5*6+……+1/99*100
=1/2-1/3+1/3-1/4+1/4-1/5+……+1/99-1/100
=1/2-1/100
=49/100