1- 2/3 -1/6 -1/12 - 1/24 ···- 1/768 =1-（1-1/3)-(1/3-1/6)-(1/6-1/12)-..-(1/384-1/768)=1-1+1/3-1/3+1/6-...+1/768=1/768 1- 2/3 -1/6 -1/12 - 1/24 ···- 1/768 =1-（1-1/3)-(1/3-1/6)-(1/6-1/12)-..-(1/384-1/768)=1-1+1/3-1/3+1/6-...+1/768=1/768