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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.

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

Solution

Answer: 233168

int sum = 0;
for (int i = 1; i < 1000; i++) {
	if (i % 3 == 0 || i % 5 == 0) {
		sum += i;
	}
}
return sum;

Discussion

Find all the multiples of 3 or 5 from small to large and sum them.