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.
Find the sum of all the multiples of 3 or 5 below 1000.
Even though the first approach that comes to mind is to make an array-ish to hold all the filtered numbers between 1 and max, it would cause unnecessary memory usage.
So, the implementation should:
- store sum as a single variable,
- iterate on all numbers,
- add the number to the sum (and skip checking for other dividers)