Java: “error: cannot find symbol”

The n variable was declared in the main method and thus is visible only in the main method, nowhere else, and certainly not inside of the calcNumFactors method. To solve this, give your calcNumFactors method an int parameter which would allow calling methods to pass an int, such as n into the method.

public static void calcNumFactors(int number) {
   // work with number in here
}

and call it like so:

int n = keyboard.nextInt(); 
calcNumFactors(n);