Find the output of the program?

public class Calculator
{
    int num = 100;
    public void calc(int num)  { this.num = num * 20;  }
    public void printNum()     { System.out.println(num); }
  
    public static void main(String[] args)
    {
        Calculator obj = new Calculator();
        obj.calc(4);
        obj.printNum();
    }
}