Fixed square() parameter error, added MDN explanation and test cases

Author: Eugenie-A

Sprint-2/1-key-errors/2.js

@@ -4,17 +4,34 @@
 // this function should square any number but instead we're going to get an error
 
 // =============> write your prediction of the error here
+// Prediction: It will throw a syntax error because 3 is not a valid parameter name.
 
+/* Original Code:
 function square(3) {
     return num * num;
 }
+*/
 
 // =============> write the error message here
+// SyntaxError: Unexpected number
 
 // =============> explain this error message here
+// MDN Reference: https://developer.mozilla.org/en-US/docs/Glossary/Identifier
+
+// JavaScript does not allow numbers to be used as variable names or parameter names.
+// Function parameters must follow the rules for valid identifiers.
+// According to MDN, an identifier may not start with a digit and must follow JavaScript's naming rules.
 
 // Finally, correct the code to fix the problem
 
 // =============> write your new code here
+function square(num) {
+    return num * num;
+}
+
+console.log(square(3)); // 9
 
+// Test cases:
 
+// console.log(square(10)); // 100
+// console.log(square(5)); // 25