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 sat here for at least one hour now not figuring it out. I've tried different solutions, and read math formulas for it etc but it won't gives me the right answer when coding it! I made two different solutions for it, which both gives me the wrong answer. The first solution gives me 265334 while the second one gives me 232169. The answer is 233168, so the second solution is closer.

I should mention this is a question from Project Euler, the first one to be precise.

Here's my code. Any ideas what's wrong?

nums = [3, 5]
max = 999

result = 0
for num in nums:
    for i in range(1,max):
        if num*i < max:
            result += num*i
print result


result = 0
for i in range(0,max):
    if i%3 == 0 or i%5 == 0:
        result += i

print result

Answer 1

You are overcomplicating things. You just need a list of numbers that are multiples of 3 or 5 which you can get easily with a list comprehension:

>>> [i for i in range(1000) if i % 3 == 0 or i % 5 == 0]

Then use sum to get the total:

>>> sum([i for i in range(1000) if i % 3 == 0 or i % 5 == 0])
<<< 233168

Or even better use a generator expression instead:

>>> sum(i for i in range(1000) if i % 3 == 0 or i % 5 == 0)

Or even better better (courtesy Exelian):

>>> sum(set(list(range(0, 1000, 3)) + list(range(0, 1000, 5))))