text: // Return the factorial of the provided integer.
  // This is a recursion example. Recursion is simply when a function calls itself.
  //
  // If the integer is represented with the letter n, a factorial is the product of all positive 
  // integers less than or equal to n.
  //
  // Factorials are often represented with the shorthand notation n!
  //
  // For example: 5! = 1 * 2 * 3 * 4 * 5 = 120
  //
  // Only integers greater than or equal to zero will be supplied to the function.
  
  let answer = 0;
  function factorialize(num) {
    "use strict";
    if (num < 0) {
      return "Must be greater than or equal to 0"; 
    } else if (num === 0) {
      answer = 1;
    } else {
      answer = num * factorialize(num-1);
    }
    return answer;
  }
  
  //console.log("5! = " + factorialize(5)); //should return 120
  console.log("10! = " + factorialize(10)); //should return 3628800
  //console.log("20! = " + factorialize(20)); //should return 2432902008176640000
  //console.log("0! = " + factorialize(0)); //should return 1
  