diff --git a/Sprint-3/4-stretch/card-validator.js b/Sprint-3/4-stretch/card-validator.js
new file mode 100644
index 000000000..6f3e5f6c2
--- /dev/null
+++ b/Sprint-3/4-stretch/card-validator.js
@@ -0,0 +1,33 @@
+// Validate whether a credit card number meets the rules from card-validator.md
+function validateCreditCardNumber(cardNumber) {
+  // Rule 1: the value must be exactly 16 characters long and contain only digits.
+  if (!/^\d{16}$/.test(cardNumber)) {
+    return false;
+  }
+
+  // Rule 2: not all digits can be the same.
+  const uniqueDigits = new Set(cardNumber);
+  if (uniqueDigits.size < 2) {
+    return false;
+  }
+
+  // Rule 3: the final digit must be even.
+  const lastDigit = Number(cardNumber[cardNumber.length - 1]);
+  if (lastDigit % 2 !== 0) {
+    return false;
+  }
+
+  // Rule 4: the sum of all digits must be greater than 16.
+  let sum = 0;
+  for (const digit of cardNumber) {
+    sum += Number(digit);
+  }
+
+  if (sum <= 16) {
+    return false;
+  }
+
+  return true;
+}
+
+module.exports = validateCreditCardNumber;
diff --git a/Sprint-3/4-stretch/card-validator.test.js b/Sprint-3/4-stretch/card-validator.test.js
new file mode 100644
index 000000000..1c0e5043b
--- /dev/null
+++ b/Sprint-3/4-stretch/card-validator.test.js
@@ -0,0 +1,26 @@
+const validateCreditCardNumber = require("./card-validator");
+
+test("returns true for a valid card number", () => {
+  expect(validateCreditCardNumber("9999777788880000")).toEqual(true);
+  expect(validateCreditCardNumber("6666666666661666")).toEqual(true);
+});
+
+test("returns false when the card contains non-digit characters", () => {
+  expect(validateCreditCardNumber("a92332119c011112")).toEqual(false);
+});
+
+test("returns false when all digits are the same", () => {
+  expect(validateCreditCardNumber("4444444444444444")).toEqual(false);
+});
+
+test("returns false when the sum of digits is not greater than 16", () => {
+  expect(validateCreditCardNumber("1111111111111110")).toEqual(false);
+});
+
+test("returns false when the final digit is odd", () => {
+  expect(validateCreditCardNumber("6666666666666661")).toEqual(false);
+});
+
+test("returns false when the number is not 16 digits long", () => {
+  expect(validateCreditCardNumber("1234")).toEqual(false);
+});
diff --git a/Sprint-3/4-stretch/password-validator.js b/Sprint-3/4-stretch/password-validator.js
index b55d527db..ab688c084 100644
--- a/Sprint-3/4-stretch/password-validator.js
+++ b/Sprint-3/4-stretch/password-validator.js
@@ -1,6 +1,43 @@
+// A list of previously used passwords that cannot be reused.
+const previousPasswords = ["Password1!", "Welcome2#", "Strong3$"];
+
 function passwordValidator(password) {
-    return password.length < 5 ? false : true
-}
+  // Ensure a password value is provided and that it is a string.
+  if (typeof password !== "string") {
+    return false;
+  }
+
+  // Password must be at least 5 characters long.
+  if (password.length < 5) {
+    return false;
+  }
+
+  // Password must contain at least one uppercase letter.
+  if (!/[A-Z]/.test(password)) {
+    return false;
+  }
+
+  // Password must contain at least one lowercase letter.
+  if (!/[a-z]/.test(password)) {
+    return false;
+  }
 
+  // Password must contain at least one number.
+  if (!/[0-9]/.test(password)) {
+    return false;
+  }
+
+  // Password must contain at least one allowed symbol.
+  if (!/[!#$%.*&]/.test(password)) {
+    return false;
+  }
+
+  // Password must not match any previous password.
+  if (previousPasswords.includes(password)) {
+    return false;
+  }
+
+  return true;
+}
 
-module.exports = passwordValidator;
\ No newline at end of file
+module.exports = passwordValidator;
diff --git a/Sprint-3/4-stretch/password-validator.test.js b/Sprint-3/4-stretch/password-validator.test.js
index 8fa3089d6..b47e4f5f4 100644
--- a/Sprint-3/4-stretch/password-validator.test.js
+++ b/Sprint-3/4-stretch/password-validator.test.js
@@ -1,4 +1,4 @@
-/* 
+/*
 Password Validation
 
 Write a program that should check if a password is valid
@@ -10,17 +10,73 @@ To be valid, a password must:
 - Have at least one English lowercase letter (a-z)
 - Have at least one number (0-9)
 - Have at least one of the following non-alphanumeric symbols: ("!", "#", "$", "%", ".", "*", "&")
-- Must not be any previous password in the passwords array. 
+- Must not be any previous password in the passwords array.
 
 You must breakdown this problem in order to solve it. Find one test case first and get that working
 */
 const isValidPassword = require("./password-validator");
-test("password has at least 5 characters", () => {
-    // Arrange
-    const password = "12345";
-    // Act
-    const result = isValidPassword(password);
-    // Assert
-    expect(result).toEqual(true);
-}
-);
\ No newline at end of file
+
+test("password is valid when it meets all rules", () => {
+  // Arrange
+  const password = "Ab1!c";
+
+  // Act
+  const result = isValidPassword(password);
+
+  // Assert
+  expect(result).toEqual(true);
+});
+
+test("password is invalid when it is shorter than 5 characters", () => {
+  const password = "A1!a";
+  const result = isValidPassword(password);
+
+  expect(result).toEqual(false);
+});
+
+test("password is invalid when it has no uppercase letter", () => {
+  const password = "abcde1!";
+  const result = isValidPassword(password);
+
+  expect(result).toEqual(false);
+});
+
+test("password is invalid when it has no lowercase letter", () => {
+  const password = "ABCDE1!";
+  const result = isValidPassword(password);
+
+  expect(result).toEqual(false);
+});
+
+test("password is invalid when it has no number", () => {
+  const password = "Abcde!";
+  const result = isValidPassword(password);
+
+  expect(result).toEqual(false);
+});
+
+test("password is invalid when it has no required symbol", () => {
+  const password = "Abcde1";
+  const result = isValidPassword(password);
+
+  expect(result).toEqual(false);
+});
+
+test("password is invalid when it has been used before", () => {
+  const password = "Password1!";
+  const result = isValidPassword(password);
+
+  expect(result).toEqual(false);
+});
+
+test("password is invalid when no password is provided", () => {
+  const result = isValidPassword();
+
+  expect(result).toEqual(false);
+});
+
+test("password is invalid when the value is not a string", () => {
+  const result = isValidPassword(12345);
+
+  expect(result).toEqual(false);
+});