Problem 1: Multiples of 3 or 5

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.

L = []

for i in range(1, 1000):
    if i % 3 == 0 or i % 5 == 0:
        L.append(i)

print(sum(L))

Click to reveal output