https://www.codewars.com/kata/514b92a657cdc65150000006
If we list all the natural numbers below 10 that are multiples of 3 or 5, we get 3, 5, 6 and 9. The sum of these multiples is 23.
Finish the solution so that it returns the sum of all the multiples of 3 or 5 below the number passed in. Additionally, if the number is negative, return 0 (for languages that do have them).
Note: If the number is a multiple of both 3 and 5, only count it once.