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.

MultipleOf3And5.java

public class MultipleOf3And5 {
	private int max;
	public MultipleOf3And5(int max){
		this.max=max;
	}
	public int calculate(){
		int sum=0;
		int j=1;
		int i=15;
		while(i<max){
			sum+=i;
			i=15*++j;
		}
		j=1;
		i=3;
		while(i<max){
			if(i%15!=0)sum+=i;
			i=3*++j;
		}
		j=1;
		i=5;
		while(i<max){
			if(i%15!=0)sum+=i;
			i=5*++j;
		}
		return sum;
	}
}

MultipleOf3And5Test.java

public class MultipleOf3And5Test {
	@Test
	public void testCalculate() {
		assertEquals(23, new MultipleOf3And5(10).calculate());
		assertEquals(233168,new MultipleOf3And5(1000).calculate());
	}
}