계산: 하나 또 4분의 1 - 9/20 + 11/30~13/42 + 15/56-17/72+19/90

계산: 하나 또 4분의 1 - 9/20 + 11/30~13/42 + 15/56-17/72+19/90

하나 또 4분의 1-9/20+11/30-13/42+15/56-17/72+19/90 = (1+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+1/4-1/4-1/5+1/5+1/6-1/6-1/7+1/7+1/8-1/8-1/8-1/9+1/10=1+1/10=11/1.