diff --git a/session-01/validators.js b/session-01/validators.js
index 56ea66d..8371820 100644
--- a/session-01/validators.js
+++ b/session-01/validators.js
@@ -7,7 +7,21 @@
   - username cannot contain special characters
 */
 function validUsername(username) {
-  return;
+  let len = username.length;
+
+  // Check for valid length
+  if (!(len >= 3 && len <= 10)) return false;
+
+  // Check for valid first letter
+  if (!(username[0] >= "A" && username[0] <= "z")) return false;
+
+  // Check for valid characters (alphanumeric)
+  for (let i = 1; i < len; i++) {
+    if (!((username[i] >= "0" && username[i] <= "9")
+        || (username[i] >= "A" && username[i] <= "z")))
+      return false;
+  }
+  return true;
 }
 
 /*
@@ -17,7 +31,21 @@ function validUsername(username) {
   - password must contain at least 1 letter, 1 number, and 1 special character
 */
 function validPassword(password) {
-  return;
+  let len = password.length;
+
+  // Check for valid length
+  if (!(len >= 10 && len <=64)) return false;
+
+  // Check for valid constraints
+  let hasLetter = false, hasNumber = false, hasSpecialChar = false;
+
+  for (let i = 0; i < len; i++) {
+    if (password[i] >= "A" && password[i] <= "z") hasLetter = true;
+    else if (password[i] >= "0" && password[i] <= "9") hasNumber = true;
+    else hasSpecialChar = true;
+  }
+  
+  return (hasLetter === true && hasNumber === true && hasSpecialChar === true);
 }
 
 module.exports = { validUsername, validPassword };
diff --git a/session-02/exercise.js b/session-02/exercise.js
index 6ade818..f9c0412 100644
--- a/session-02/exercise.js
+++ b/session-02/exercise.js
@@ -3,7 +3,10 @@
   For example, for the input ["cat", "hat"], return ["CAT", "HAT"]
 */
 function transformArrayToUpper(listOfStrings) {
-  return;
+  let transformedArray = listOfStrings.map((string) => {
+    return string.toUpperCase();
+  });
+  return transformedArray;
 }
 
 /*
@@ -16,7 +19,11 @@ function transformArrayToUpper(listOfStrings) {
     the function should return 51
 */
 function sumOfAllAges(listOfStudentObjects) {
-  return;
+  let sum = 0;
+  listOfStudentObjects.forEach((student) => {
+    if (student.age) sum += student.age;
+  });
+  return sum;
 }
 
 module.exports = { transformArrayToUpper, sumOfAllAges };