Sn=1/2!+2/3!+3/4!+.......+n/(n+1)!Zn=1/2!+1/3!+1/4!+ …… +1/(n+1)!两式相加 Sn+Zn=1+1/2!+1/3!+…… +1/n!Sn=1+1/2!+1/3!+…… +1/n!-Zn=1-1/(n+1)!
