There is a string of numbers, arranged in the following order: 1 / 2 - 1 / 3 2 / 3 - 1 / 4 2 / 4 - 3 / 4 1 / 5 - 2 / 5 3 / 5 - 4 / 5 There is a string of numbers, arranged in the following order: 1 / 2 - 1 / 3 2 / 3 - 1 / 4 2 / 4 - 3 / 4 1 / 5 - 2 / 5 3 / 5 - 4 / 5

There is a string of numbers, arranged in the following order: 1 / 2 - 1 / 3 2 / 3 - 1 / 4 2 / 4 - 3 / 4 1 / 5 - 2 / 5 3 / 5 - 4 / 5 There is a string of numbers, arranged in the following order: 1 / 2 - 1 / 3 2 / 3 - 1 / 4 2 / 4 - 3 / 4 1 / 5 - 2 / 5 3 / 5 - 4 / 5

-9/15
Even numbers are negative and singular numbers are positive
Because if the denominator is n, there are n-1 numbers with this as the denominator
So 1 + 2 +... N-1