(1-1/15)+(1-1/35)+(1-1/63)+(1-1/99)+(1-1/143)+(1-1/195)+(1-1/255)+(1-1/323)+(1-1/399)+(1-1/483)=(1+1+.1)-(1/15-1/35-1/63-.1/399-1/483)=9-(1/3-1/5+1/5-1/7+1/7-1/9+.1/19-1/21+1/21-1/23)=9-(1/3-1/23)=9-2...错了，应9减1/2*（1/3-1/5……1/21-1/23）嗯，=9-1/2(1/3-1/5+1/5-1/7+1/7-1/9+............1/19-1/21+1/21-1/23)=9-1/2(1/3-1/23)=9-10/69=8又59/69 疏忽了忘谅解