Java - Calculator Methods

public class CalculatorMethods {
    public static void main(String[] args) {
        System.out.println(minus(10, 5)); // 5
        System.out.println(multiply(5, 5)); // 25
        System.out.println(divide(15, 3)); // 5
    }

    public static double minus(double a, double b) {
        return a + -b;
    }

    public static double multiply(double a, double b) {
        double c = 0;
        for(double i = 0; i < a; i++) {
            c += b;
        }

        return c;
    }

    public static double divide(double a, double b) {
        double c = 0;
        while(a != 0) {
            a = minus(a, b);
            c++;
        }

        return c;
    }
}