Answer is 233168 pragmatically.
I did not use the Math to get the answer.
public class Main { public static int multiple3and5below1000() { int sum = 0; for (int i = 3; i < 1000; i++) { if ((i >= 3 && ((i % 3) == 0) || (i >= 5 && ((i % 5) == 0)))) sum += i; } return sum; } public static void main(String[] args) { System.out.println(multiple3and5below1000()); } }