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.

This one is pretty simple from the get-go. Simply iterate through numbers `1..999`

and check if they are a multiple of 3 or 5. If they are, add them to the total.

Python Implementation