Completed getOrdinalNumber implementation - passes all 5 Jest test cases

Author: Eugenie-A

Sprint-3/2-practice-tdd/get-ordinal-number.js

@@ -1,5 +1,23 @@
 function getOrdinalNumber(num) {
-  return "1st";
+  // Last digit determines st/nd/rd for most numbers
+  const lastDigit = num % 10;
+  // Last two digits needed to handle special,
+  // teen cases (11th, 12th, 13th)
+  const lastTwo = num % 100;
+
+  // Special rule: numbers ending in 11, 12 or 13 always use "th"
+  if (lastTwo === 11 || lastTwo === 12 || lastTwo === 13) {
+    return num + "th";
+  }
+
+  // Ending in 1 → "st"
+  if (lastDigit === 1) return num + "st";
+  // Ending in 2 → "nd"
+  if (lastDigit === 2) return num + "nd";
+  // Ending in 3 → "rd"
+  if (lastDigit === 3) return num + "rd";
+  // All other endings (0, 4-9 and anything after teen check) → "th"
+  return num + "th";
 }
 
 module.exports = getOrdinalNumber;