How it works

Code:

public static int factorial(int n){
    //stop
    if (n == 1){
        return(1);
    }
    //recursion
    return(num * factorial(n-1));
 }

Basically, by calling factorial (n), you will call factorial (n-1) until n == 1, in which it will return 1. This leads to a chain of n*n-1*n-2 etc etc etc until we hit the stop.