Created by Julien Palard

Find the sum of all natural numbers below 1000 (<1000) that are multiples of 3 or 5.

If we list all the natural numbers below 20 (<20) that are multiples of 3 or 5, we get 3, 5, 6, 9, 10, 12, 15, 18. The sum of these multiples is 78.

Note that 15 is only counted once.

Find the sum of all natural numbers below 1000 (<1000) that are multiples of 3 or 5, and print the result (numbers divisible by 3 and 5 should be counted a single time).