答案

來源: 於 2024-07-15 20:22:55 [舊帖] [給我悄悄話] 本文已被閱讀：次

3/10+3/40+3/88+3/154+3/238+3/340
      =(3/2x5)+(3/5x8)+(3/8x11)+(3/11x14)+(3/14x17)+(3/17x20)
      =(1/2-1/5)+(1/5-1/8)+(1/8-1/11)+(1/11-1/14)+(1/14-1/17)+(1/17-1/20)
      = 1/2 - 1/20
      = 0.5 - 0.05
      = 0.45