求和1/2!+2/3!+3/4!+……n/(n+1)!
问题描述：
求和1/2!+2/3!+3/4!+……n/(n+1)!
答
1/2!+2/3!+3/4!+……n/(n+1)!
=(1/1-1/2!)+(1/2!-1/3!)+(1/3!-1/4!)+...+[1/n!-1/(n+1)!]
=1-1/(n+1)!