(1+1/2)-(2+5/6)+(3+1/12)-(4+19/20)+(5+1/30)-(6+41/42)+(7+1/56)－﹙8＋71／72﹚＋﹙9＋1／90﹚＝

1+1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72+1/90
=1+1/2+1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6+1/6-1/7+1/7-1/8+1/8-1/9+1/9-1/10
=1+1-1/10
=19/10
你前面算对没就不知道了,