解答: 2/3!+3/4!+4/5!+……+99/100!= (3-1)/3!+(4-1)/4!+(5-1)/5!+……+(100-1)/100!=3/3!-1/3!+4/4!-1/4!+5/5!-1/5!+.........+100/100!-1/100!=1/2!-1/3!+1/3!-1/4!+1/4!-1/5!+........+1/99!-1/100!=1/2!-1/100!=1/2-1/100!