Description changed, not to what you wrote, but I think it addresses the problem.

The description is very ambiguous, especially the Input -> Output code block.

I finally solved a 5 or 6 kyu that was worth 8 kyu hahahaha

My answer was:

(summation 3) ->  6 (1+2+3)
(summation 8) -> 36 (1+2+3+4+5+6+7+8)

But don't pass the test, just need the total of the sum LOL.

The fixed description is:

Summation (Adition)

Write a program that finds the summation (adition) of every number from 1 to number.

For example
(Input -> Output):

(summation 2) -> 3
(summation 8) -> 36