Until this question, the course never teach about passing the parameter. Can someone help?

Passing a parameter to an argument: "sqr()" is a method. So in your main method, you can invoke this method anytime by doing sqr() But if you realize the sqr() method has an arguement called int a: public static int sqr(int a) { return a * a; } This means you have to pass an argument, in this case, an integer (any number), to the method for it to run. i.e. sqr(5); Then the method will take into effect. For instance, I can now declare a new integer that uses this method: int newInteger = sqr(5); Your "newInteger" value would now be 25