1、 One half, one third, one fourth, one fifth, one sixth What's the number 50? What's the number 2013?
According to the meaning of the title, we can get such a rule
When the remainder is 2, the number is - 1 / N, otherwise it is 1 / n
therefore
50 △ 4 = 12, the remainder is 2, so the fiftieth number is - 1 / 50
2013 △ 4 = 503, the remainder is 1, not 2, so the number of 2013 is 1 / 2013