1+2又1/8+3又1/12+4又1/20+5又1/30-6又1/42+7又1/56+8又1/42+9又1/42

1+2又1/8+3又1/12+4又1/20+5又1/30-6又1/42+7又1/56+8又1/42+9又1/42
1+2又1/8+3又1/12+4又1/20+5又1/30-6又1/42+7又1/56+8又1/42+9又1/42

1+2又1/8+3又1/12+4又1/20+5又1/30-6又1/42+7又1/56+8又1/42+9又1/42
1+2又1/6+3又1/12+4又1/20+5又1/30-6又1/42+7又1/56+8又1/72+9又1/110
=(1+2+3+4+5+6+7+8+9)+(1/6+1/12+1/20+1/30+1/42+1/56+1/72+/110)
=45+(1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6+1/7-1/8+1/8-1/9+1/9-1/10+1/10-1/11)
=45+1/2-1/11
=45+9/22
=45又9/22