2分之1加6分之5加12分之11加20分之19加30分之29加42分之41.加到9900分之9899等于

1/2+5/6+11/12+19/20+29/30+41/42+...+9899/9900
=1-1/2+1-1/6+1-1/12+1-1/20+1-1/30+...+1-1/9900
=99-(1/2+1/6+1/12+...+1/9900)
=99-(1-1/2+1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6+...+1/99-1/100)
=99-(1-1/100)
=98又1/100