How to find the sum of all the multiples of 3 or 5 below 1000 in Python?

Question

Not sure if I should\'ve posted this on math.stackexchange instead, but it includes more programming so I posted it here.

The question seems really simple, but I\'ve

Answer 1

I know this is from 6 years ago but I just thought id share a solution that found from a math formula that I thought was interesting as it removes the need to loop through all the numbers.

https://math.stackexchange.com/a/9305

def sum_of_two_multiples(nums, maxN):
    "takes tuple returns multiples under maxN (max number - 1)"
    n1, n2 = nums = nums[:2]
    maxN -= 1
    def k(maxN, kx):
        n = int(maxN / kx)
        return int(kx * (0.5 * n * (n+1)))

return sum([k(maxN, n) for n in nums]) - k(maxN, n1*n2)

Outputs the follows

print(sum_of_two_multiples((3,5), 10))
# 23
print(sum_of_two_multiples((3,5), 1000))
# 233168
print(sum_of_two_multiples((3,5), 10**12))
# 233333333333166658682880