1+3 6/1+5 12/1+7 20/1+9 30/1+11 42/1+13 56/1+15 72/1+17 90/1

1+3 6/1+5 12/1+7 20/1+9 30/1+11 42/1+13 56/1+15 72/1+17 90/1+19 110/1
=(1+3+5+7+9+11+13+15+17+19)+(1/6+1/12+1/20+-----+1/110)
=100+(1/2-1/3+1/3-1/4+1/4-1/5+-----+1/10-1/11)
=100+(1/2-1/11)
=100+9/22
=100又9/22