Problem 1

Solution to Problem 1. Written in Python.

Problem: 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.

sum_num = 0
for x in range(1, 1000):
    if (x % 3 == 0) or (x % 5 == 0):
        sum_num += x

print sum_num