更新1:
第一個回答者,我唔知你個答案點黎,唔該補充吓啦! 答案應該得一個,唔係好多個架!
更新2:
1/1x2 + 1/2x3 + 1/3x4 + 1/4x5 ...... 1/99999x100000 = a/b