1+1/2-5/6+7/12-9/20+11/30-13/42+15/56 =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+..........................................................+1/8 =9/8
原式=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+..........................................................+1/8 =9/8