[#1] Multiples of 3 and 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.

Q: Find the sum of all the multiples of 3 or 5 below 1000.

def problem1(a, b, bl):
        '''
 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 a or b below "bl".
 '''
        result = 0
        for i in range(1, bl):
            temp = a * i #temp is multiples of a
            if temp >= bl:
                break
            result += temp
        for i in range(1, bl):
            temp = b * i #temp is multiples of b
            if temp >= bl:
                break
            if temp % 3 == 0:#temp is multiples of b but no a, so temp is not multiples of a*b
                continue
            result += temp
        return result

def problem1(a, b, bl):
        '''
 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 a or b below "bl".
 '''
        result = 0

        c = (bl - 1) // a #have c number multiples of a
        d = (bl - 1) // b #have d number multiples of b
        e = (bl - 1) // (a * b) #have e number multiples of a * b
        for i in range(1, c + 1):
            result += a * i #a * i is multiples of a
        for i in range(1, d + 1):
            result += b * i #b * i is multiples of b
        for i in range(1, e + 1):
            result -= a * b * i
        return result