Write a program to find remainder of dividing two numbers, without using % operator? In Java

Question

How to find the remainder of dividing two numbers without using the modulo operator!! My teacher gave me this exact exercise and It's only my 5th lecture in a course called programming fundamentals.
I have already tried this equation,

a%b = a - (a/b)*b

but it always returns zero!

Answer 1

I've just tried this

public static void main (String [] args){
    int a = 50;
    int b = 9;

    int c = a%b;
    int d = a - (a/b)*b;

    System.out.println(c);
    System.out.println(d);
}

And it seems to work. What types are your variables?