diff --git a/sprint-3-stretch-exercises/card-validator.js b/sprint-3-stretch-exercises/card-validator.js
new file mode 100644
index 000000000..0126a9979
--- /dev/null
+++ b/sprint-3-stretch-exercises/card-validator.js
@@ -0,0 +1,39 @@
+function isValidCreditCardNumber(cardNumber){
+    if(cardNumber.length !== 16) {
+        return false;
+    }
+
+    const allowedCharacters = "0123456789";
+    for(let i = 0; i < cardNumber.length; i++) {
+        const character = cardNumber[i];
+        if(!allowedCharacters.includes(character)) {
+            return false;
+        }
+    }
+
+    const firstDigit = cardNumber[0];
+    let foundDifferentDigit = false;
+    for(let i = 0; i < cardNumber.length; i++) {
+        if(cardNumber[i] !== firstDigit) {
+            foundDifferentDigit = true;
+        }
+    }
+    if(foundDifferentDigit === false){
+        return false;
+    }
+
+    const lastDigit = Number(cardNumber[15]);
+    if(lastDigit % 2 !== 0) {
+        return false;
+    }
+
+    let sum = 0;
+    for(let i = 0; i < cardNumber.length; i++){
+        sum += Number(cardNumber[i]);
+    }
+    if(sum <= 16){
+        return false;
+    }
+
+    return true;
+}
\ No newline at end of file
diff --git a/sprint-3-stretch-exercises/find.js b/sprint-3-stretch-exercises/find.js
index c7e79a2f2..f04859dd2 100644
--- a/sprint-3-stretch-exercises/find.js
+++ b/sprint-3-stretch-exercises/find.js
@@ -20,6 +20,13 @@ console.log(find("code your future", "z"));
 // Pay particular attention to the following:
 
 // a) How the index variable updates during the call to find
+// "Index" starts at 0 and increases by 1 when there is no match.
+
 // b) What is the if statement used to check
+// It's checking whether the character at the current position equals the character we are looking for.
+
 // c) Why is index++ being used?
+// Without index++ there would be an infinite loop, whereby index would never change.
+
 // d) What is the condition index < str.length used for?
+// It is used to stop the loop as soon as it reaches the end of the string, so we don't look at positions that don't exist.
diff --git a/sprint-3-stretch-exercises/password-validator.js b/sprint-3-stretch-exercises/password-validator.js
index ac70324a5..c8cd9164e 100644
--- a/sprint-3-stretch-exercises/password-validator.js
+++ b/sprint-3-stretch-exercises/password-validator.js
@@ -1,3 +1,14 @@
-export function isValidPassword(password) {
-  return password.length >= 5;
+export function isValidPassword(password, previousPassword = []) {
+  if (/[A-Z]/.test(password)) 
+    return false;
+  if (/[a-z]/.test(password)) 
+    return false;
+  if (/[0-9]/.test(password)) 
+    return false;
+  if (/[!#$%.*&]/.test(password)) 
+    return false;
+  if (previousPassword.includes(password)) 
+    return false;
+  
+  return true;
 }
diff --git a/sprint-3-stretch-exercises/password-validator.test.js b/sprint-3-stretch-exercises/password-validator.test.js
index 2a58a0fb6..4d3b8589f 100644
--- a/sprint-3-stretch-exercises/password-validator.test.js
+++ b/sprint-3-stretch-exercises/password-validator.test.js
@@ -15,12 +15,43 @@ To be valid, a password must:
 You must breakdown this problem in order to solve it. Find one test case first and get that working
 */
 import { isValidPassword } from "./password-validator.js";
+
 test("password has at least 5 characters", () => {
     // Arrange
-    const password = "12345";
+    const password = "Ab7#";
     // Act
     const result = isValidPassword(password);
     // Assert
-    expect(result).toEqual(true);
-}
-);
\ No newline at end of file
+    expect(result).toEqual(false);
+});
+
+test("password has at least one uppercase letter", () => {
+    const password = "ab7#x";
+    const result = isValidPassword(password);
+    expect(result).toEqual(false);
+});
+
+test("password has at least one lowercase letter", () => {
+    const password = "AB7#X";
+    const result = isValidPassword(password);
+    expect(result).toEqual(false);
+});
+
+test("password has at least one number", () => {
+    const password = "Abc#x";
+    const result = isValidPassword(password);
+    expect(result).toEqual(false);
+});
+
+test("password has at least one non-alphanumeric symbol", () => {
+    const password = "Ab7nx";
+    const result = isValidPassword(password);
+    expect(result).toEqual(false);
+});
+
+test("password must not be a previous password", () => {
+    const password = "Ab7#x";
+    const previousPassword = ["Ab7#x"];
+    const result = isValidPassword(password, previousPassword);
+    expect(result).toEqual(false);
+});
\ No newline at end of file