diff --git a/Sprint-1/1-key-exercises/1-count.js b/Sprint-1/1-key-exercises/1-count.js
index 117bcb2b6..e647ba0b8 100644
--- a/Sprint-1/1-key-exercises/1-count.js
+++ b/Sprint-1/1-key-exercises/1-count.js
@@ -3,4 +3,4 @@ let count = 0;
 count = count + 1;
 
 // Line 1 is a variable declaration, creating the count variable with an initial value of 0
-// Describe what line 3 is doing, in particular focus on what = is doing
+// Describe what line 3 is doing, in particular focus on what = is doing  --> = means a assignment on itself +1
diff --git a/Sprint-1/1-key-exercises/2-initials.js b/Sprint-1/1-key-exercises/2-initials.js
index 47561f617..611678dc0 100644
--- a/Sprint-1/1-key-exercises/2-initials.js
+++ b/Sprint-1/1-key-exercises/2-initials.js
@@ -7,5 +7,8 @@ let lastName = "Johnson";
 
 let initials = ``;
 
+initials = `${firstName[0]}, ${middleName[0]}, ${lastName[0]}`;
+
 // https://www.google.com/search?q=get+first+character+of+string+mdn
 
+//console.log(initials);
diff --git a/Sprint-1/1-key-exercises/3-paths.js b/Sprint-1/1-key-exercises/3-paths.js
index ab90ebb28..852b0a8a9 100644
--- a/Sprint-1/1-key-exercises/3-paths.js
+++ b/Sprint-1/1-key-exercises/3-paths.js
@@ -17,7 +17,18 @@ console.log(`The base part of ${filePath} is ${base}`);
 // Create a variable to store the dir part of the filePath variable
 // Create a variable to store the ext part of the variable
 
-const dir = ;
-const ext = ;
+const dir = filePath.slice(0, filePath.lastIndexOf("/"));
+const ext = filePath.slice(filePath.lastIndexOf(".") + 1);
 
-// https://www.google.com/search?q=slice+mdn
\ No newline at end of file
+console.log(dir);
+console.log(ext);
+
+/*
+Explanation:
+
+filePath.lastIndexOf(".") finds the position of the last dot in the path.
+
+slice() extracts the substring starting one position after the dot (hence +1), giving just the extension without the dot.
+*/
+
+// https://www.google.com/search?q=slice+mdn
diff --git a/Sprint-1/1-key-exercises/4-random.js b/Sprint-1/1-key-exercises/4-random.js
index 292f83aab..6d68fa228 100644
--- a/Sprint-1/1-key-exercises/4-random.js
+++ b/Sprint-1/1-key-exercises/4-random.js
@@ -3,7 +3,10 @@ const maximum = 100;
 
 const num = Math.floor(Math.random() * (maximum - minimum + 1)) + minimum;
 
-// In this exercise, you will need to work out what num represents?
-// Try breaking down the expression and using documentation to explain what it means
-// It will help to think about the order in which expressions are evaluated
+// In this exercise, you will need to work out what num represents? --> num gives a random number between 1 and 100
+// Try breaking down the expression and using documentation to explain what it means  --> Math.floor() give the rounded number below
+// --> Math.random give a number between 0 and 1 but never 1
+// It will help to think about the order in which expressions are evaluated --> first what is in parenthesis
 // Try logging the value of num and running the program several times to build an idea of what the program is doing
+
+console.log(num);
diff --git a/Sprint-1/2-mandatory-errors/0.js b/Sprint-1/2-mandatory-errors/0.js
index cf6c5039f..d68d870e5 100644
--- a/Sprint-1/2-mandatory-errors/0.js
+++ b/Sprint-1/2-mandatory-errors/0.js
@@ -1,2 +1,2 @@
 This is just an instruction for the first activity - but it is just for human consumption
-We don't want the computer to run these 2 lines - how can we solve this problem?
\ No newline at end of file
+We don't want the computer to run these 2 lines - how can we solve this problem? --> with /*     */
\ No newline at end of file
diff --git a/Sprint-1/2-mandatory-errors/1.js b/Sprint-1/2-mandatory-errors/1.js
index 7a43cbea7..22570713c 100644
--- a/Sprint-1/2-mandatory-errors/1.js
+++ b/Sprint-1/2-mandatory-errors/1.js
@@ -2,3 +2,4 @@
 
 const age = 33;
 age = age + 1;
+// --> let age =33; instead of using const
diff --git a/Sprint-1/2-mandatory-errors/2.js b/Sprint-1/2-mandatory-errors/2.js
index e09b89831..fe9df0797 100644
--- a/Sprint-1/2-mandatory-errors/2.js
+++ b/Sprint-1/2-mandatory-errors/2.js
@@ -3,3 +3,4 @@
 
 console.log(`I was born in ${cityOfBirth}`);
 const cityOfBirth = "Bolton";
+//--> cityOfBirth must be declared before the console.log of cityOfBirth
diff --git a/Sprint-1/2-mandatory-errors/3.js b/Sprint-1/2-mandatory-errors/3.js
index ec101884d..d42223e4d 100644
--- a/Sprint-1/2-mandatory-errors/3.js
+++ b/Sprint-1/2-mandatory-errors/3.js
@@ -7,3 +7,5 @@ const last4Digits = cardNumber.slice(-4);
 // Then run the code and see what error it gives.
 // Consider: Why does it give this error? Is this what I predicted? If not, what's different?
 // Then try updating the expression last4Digits is assigned to, in order to get the correct value
+console.log(last4Digits);
+//--> .slice() works only with a string --> add '4533'
diff --git a/Sprint-1/2-mandatory-errors/4.js b/Sprint-1/2-mandatory-errors/4.js
index 21dad8c5d..161b4bd9b 100644
--- a/Sprint-1/2-mandatory-errors/4.js
+++ b/Sprint-1/2-mandatory-errors/4.js
@@ -1,2 +1,4 @@
 const 12HourClockTime = "20:53";
-const 24hourClockTime = "08:53";
\ No newline at end of file
+const 24hourClockTime = "08:53";
+
+//--> we mustn't begin a name's variable with integer
\ No newline at end of file
diff --git a/Sprint-1/3-mandatory-interpret/1-percentage-change.js b/Sprint-1/3-mandatory-interpret/1-percentage-change.js
index e24ecb8e1..5558fcb15 100644
--- a/Sprint-1/3-mandatory-interpret/1-percentage-change.js
+++ b/Sprint-1/3-mandatory-interpret/1-percentage-change.js
@@ -1,5 +1,5 @@
-let carPrice = "10,000";
-let priceAfterOneYear = "8,543";
+let carPrice = 10000;
+let priceAfterOneYear = 8543;
 
 carPrice = Number(carPrice.replaceAll(",", ""));
 priceAfterOneYear = Number(priceAfterOneYear.replaceAll("," ""));
@@ -11,12 +11,13 @@ console.log(`The percentage change is ${percentageChange}`);
 
 // Read the code and then answer the questions below
 
-// a) How many function calls are there in this file? Write down all the lines where a function call is made
+// a) How many function calls are there in this file? Write down all the lines where a function call is made --> Number() line4 and line5
 
-// b) Run the code and identify the line where the error is coming from - why is this error occurring? How can you fix this problem?
+// b) Run the code and identify the line where the error is coming from - why is this error occurring? How can you fix this problem? --> the 2 variables are strings and Number returns a integer
 
-// c) Identify all the lines that are variable reassignment statements
+// c) Identify all the lines that are variable reassignment statements -->4,5,7,8
 
-// d) Identify all the lines that are variable declarations
+// d) Identify all the lines that are variable declarations  -->1,2,7,8
 
 // e) Describe what the expression Number(carPrice.replaceAll(",","")) is doing - what is the purpose of this expression?
+// --> Number gives the integer or real number and .replace() works with a string and replace all "," by nothing ""
\ No newline at end of file
diff --git a/Sprint-1/3-mandatory-interpret/2-time-format.js b/Sprint-1/3-mandatory-interpret/2-time-format.js
index 47d239558..c69877bb0 100644
--- a/Sprint-1/3-mandatory-interpret/2-time-format.js
+++ b/Sprint-1/3-mandatory-interpret/2-time-format.js
@@ -1,4 +1,4 @@
-const movieLength = 8784; // length of movie in seconds
+const movieLength = 65; // length of movie in seconds
 
 const remainingSeconds = movieLength % 60;
 const totalMinutes = (movieLength - remainingSeconds) / 60;
@@ -11,15 +11,16 @@ console.log(result);
 
 // For the piece of code above, read the code and then answer the following questions
 
-// a) How many variable declarations are there in this program?
+// a) How many variable declarations are there in this program?  -> 6 because in the same time, there are assignments
 
-// b) How many function calls are there?
+// b) How many function calls are there?  --> 0 because console.log() is a method
 
-// c) Using documentation, explain what the expression movieLength % 60 represents
+// c) Using documentation, explain what the expression movieLength % 60 represents --> % is the modulo which gives the remaining
 // https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Arithmetic_Operators
 
-// d) Interpret line 4, what does the expression assigned to totalMinutes mean?
+// d) Interpret line 4, what does the expression assigned to totalMinutes mean? -->We remove the seconds and divide with 60 to have the remaining time without the seconds
 
-// e) What do you think the variable result represents? Can you think of a better name for this variable?
+// e) What do you think the variable result represents? Can you think of a better name for this variable? -->lengthOfMovieHours
 
 // f) Try experimenting with different values of movieLength. Will this code work for all values of movieLength? Explain your answer
+//--> not with a negative number
diff --git a/Sprint-1/3-mandatory-interpret/3-to-pounds.js b/Sprint-1/3-mandatory-interpret/3-to-pounds.js
index 60c9ace69..166001448 100644
--- a/Sprint-1/3-mandatory-interpret/3-to-pounds.js
+++ b/Sprint-1/3-mandatory-interpret/3-to-pounds.js
@@ -2,19 +2,24 @@ const penceString = "399p";
 
 const penceStringWithoutTrailingP = penceString.substring(
   0,
-  penceString.length - 1
+  penceString.length - 1 // take only 399
 );
+console.log(penceStringWithoutTrailingP);
+
+const paddedPenceNumberString = penceStringWithoutTrailingP.padStart(3, "0"); //The padStart() adds characters to the beginning of a string until the string reaches a specified total length
+console.log(paddedPenceNumberString);
 
-const paddedPenceNumberString = penceStringWithoutTrailingP.padStart(3, "0");
 const pounds = paddedPenceNumberString.substring(
   0,
-  paddedPenceNumberString.length - 2
+  paddedPenceNumberString.length - 2 // gives only the pound
 );
+console.log(pounds);
 
 const pence = paddedPenceNumberString
   .substring(paddedPenceNumberString.length - 2)
   .padEnd(2, "0");
 
+console.log(pence);
 console.log(`£${pounds}.${pence}`);
 
 // This program takes a string representing a price in pence
diff --git a/Sprint-1/4-stretch-explore/objects.md b/Sprint-1/4-stretch-explore/objects.md
index 0216dee56..204ec32f5 100644
--- a/Sprint-1/4-stretch-explore/objects.md
+++ b/Sprint-1/4-stretch-explore/objects.md
@@ -14,3 +14,4 @@ Answer the following questions:
 
 What does `console` store?
 What does the syntax `console.log` or `console.assert` mean? In particular, what does the `.` mean?
+//--> console is a object. the . call the property or a method
diff --git a/Sprint-2/1-key-errors/0.js b/Sprint-2/1-key-errors/0.js
index 653d6f5a0..f68dccb78 100644
--- a/Sprint-2/1-key-errors/0.js
+++ b/Sprint-2/1-key-errors/0.js
@@ -2,12 +2,15 @@
 //  =============> write your prediction here
 
 // call the function capitalise with a string input
-// interpret the error message and figure out why an error is occurring
+// interpret the error message and figure out why an error is occurring  --> str is already declared when the function is declared
 
 function capitalise(str) {
-  let str = `${str[0].toUpperCase()}${str.slice(1)}`;
-  return str;
+  let str2 = `${str[0].toUpperCase()}${str.slice(1)}`;
+  return str2;
 }
 
 // =============> write your explanation here
 // =============> write your new code here
+
+let test = "tamTamyngo";
+console.log(capitalise(test));
diff --git a/Sprint-2/1-key-errors/1.js b/Sprint-2/1-key-errors/1.js
index f2d56151f..7442fef6a 100644
--- a/Sprint-2/1-key-errors/1.js
+++ b/Sprint-2/1-key-errors/1.js
@@ -1,18 +1,18 @@
 // Predict and explain first...
 
 // Why will an error occur when this program runs?
-// =============> write your prediction here
+// =============> write your prediction here              --> decimalNumber is a variable which is declarer already
 
 // Try playing computer with the example to work out what is going on
 
 function convertToPercentage(decimalNumber) {
-  const decimalNumber = 0.5;
+  // const decimalNumber = 0.5;
   const percentage = `${decimalNumber * 100}%`;
 
   return percentage;
 }
-
-console.log(decimalNumber);
+const test = 0.25;
+console.log(convertToPercentage(test));
 
 // =============> write your explanation here
 
diff --git a/Sprint-2/1-key-errors/2.js b/Sprint-2/1-key-errors/2.js
index aad57f7cf..8aef95639 100644
--- a/Sprint-2/1-key-errors/2.js
+++ b/Sprint-2/1-key-errors/2.js
@@ -1,20 +1,23 @@
-
 // Predict and explain first BEFORE you run any code...
 
 // this function should square any number but instead we're going to get an error
 
 // =============> write your prediction of the error here
 
-function square(3) {
+/* function square(3) {
     return num * num;
-}
+} */
 
 // =============> write the error message here
 
 // =============> explain this error message here
 
-// Finally, correct the code to fix the problem
+// Finally, correct the code to fix the problem   --> need a parameter num
 
 // =============> write your new code here
 
+function square(num) {
+  return num * num;
+}
 
+console.log(square(3));
diff --git a/Sprint-2/2-mandatory-debug/0.js b/Sprint-2/2-mandatory-debug/0.js
index b27511b41..7d980addd 100644
--- a/Sprint-2/2-mandatory-debug/0.js
+++ b/Sprint-2/2-mandatory-debug/0.js
@@ -1,14 +1,20 @@
-// Predict and explain first...
+// Predict and explain first... --> the function must give the multiplication of 2 numbers as argument
 
-// =============> write your prediction here
+// =============> write your prediction here    don't use a return but a console.log which is not reusable later
 
-function multiply(a, b) {
+/* function multiply(a, b) {
   console.log(a * b);
 }
 
 console.log(`The result of multiplying 10 and 32 is ${multiply(10, 32)}`);
-
+ */
 // =============> write your explanation here
 
 // Finally, correct the code to fix the problem
 //  =============> write your new code here
+
+function multiply(a, b) {
+  return a * b;
+}
+
+console.log(`The result of multiplying 10 and 32 is ${multiply(10, 32)}`);
diff --git a/Sprint-2/2-mandatory-debug/1.js b/Sprint-2/2-mandatory-debug/1.js
index 37cedfbcf..57d7b68b0 100644
--- a/Sprint-2/2-mandatory-debug/1.js
+++ b/Sprint-2/2-mandatory-debug/1.js
@@ -1,13 +1,17 @@
-// Predict and explain first...
+// Predict and explain first...  --> sum() must return a sum of a and b but error because of ; after return
 //  =============> write your prediction here
 
-function sum(a, b) {
+/* function sum(a, b) {
   return;
   a + b;
-}
+} */
 
 console.log(`The sum of 10 and 32 is ${sum(10, 32)}`);
 
 // =============> write your explanation here
 // Finally, correct the code to fix the problem
 //  =============> write your new code here
+
+function sum(a, b) {
+  return a + b;
+}
diff --git a/Sprint-2/2-mandatory-debug/2.js b/Sprint-2/2-mandatory-debug/2.js
index 57d3f5dc3..848c17ff4 100644
--- a/Sprint-2/2-mandatory-debug/2.js
+++ b/Sprint-2/2-mandatory-debug/2.js
@@ -1,24 +1,30 @@
 // Predict and explain first...
 
 // Predict the output of the following code:
-// =============> Write your prediction here
+// =============> Write your prediction here  --> a integer is transformed to a string and .slice() take only the last character
 
-const num = 103;
+/* const num = 103;
 
 function getLastDigit() {
   return num.toString().slice(-1);
-}
+} */
 
-console.log(`The last digit of 42 is ${getLastDigit(42)}`);
+/* console.log(`The last digit of 42 is ${getLastDigit(42)}`);
 console.log(`The last digit of 105 is ${getLastDigit(105)}`);
-console.log(`The last digit of 806 is ${getLastDigit(806)}`);
+console.log(`The last digit of 806 is ${getLastDigit(806)}`); */
 
 // Now run the code and compare the output to your prediction
 // =============> write the output here
-// Explain why the output is the way it is
+// Explain why the output is the way it is  --> because we use num
 // =============> write your explanation here
 // Finally, correct the code to fix the problem
 // =============> write your new code here
+function getLastDigit(num) {
+  return num.toString().slice(-1);
+}
+console.log(`The last digit of 42 is ${getLastDigit(42)}`);
+console.log(`The last digit of 105 is ${getLastDigit(105)}`);
+console.log(`The last digit of 806 is ${getLastDigit(806)}`);
 
 // This program should tell the user the last digit of each number.
 // Explain why getLastDigit is not working properly - correct the problem
diff --git a/Sprint-2/3-mandatory-implement/1-bmi.js b/Sprint-2/3-mandatory-implement/1-bmi.js
index 17b1cbde1..9e0fa49f6 100644
--- a/Sprint-2/3-mandatory-implement/1-bmi.js
+++ b/Sprint-2/3-mandatory-implement/1-bmi.js
@@ -15,5 +15,9 @@
 // It should return their Body Mass Index to 1 decimal place
 
 function calculateBMI(weight, height) {
-    // return the BMI of someone based off their weight and height
-}
\ No newline at end of file
+  // return the BMI of someone based off their weight and height
+  let BMI = weight / (height * height);
+  return Math.round(BMI * 10) / 10; // Return rounded BMI with one decimal place as a number (not string)
+}
+
+console.log(calculateBMI(70, 1.73));
diff --git a/Sprint-2/3-mandatory-implement/2-cases.js b/Sprint-2/3-mandatory-implement/2-cases.js
index 5b0ef77ad..62be2bc19 100644
--- a/Sprint-2/3-mandatory-implement/2-cases.js
+++ b/Sprint-2/3-mandatory-implement/2-cases.js
@@ -14,3 +14,9 @@
 // You will need to come up with an appropriate name for the function
 // Use the MDN string documentation to help you find a solution
 // This might help https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/toUpperCase
+
+let toUp = function (str) {
+  let newStr = str.toUpperCase().replace(/ /g, "_");
+  return newStr;
+};
+console.log(toUp("lord of the rings"));
diff --git a/Sprint-2/3-mandatory-implement/3-to-pounds.js b/Sprint-2/3-mandatory-implement/3-to-pounds.js
index 6265a1a70..e0c613abe 100644
--- a/Sprint-2/3-mandatory-implement/3-to-pounds.js
+++ b/Sprint-2/3-mandatory-implement/3-to-pounds.js
@@ -4,3 +4,25 @@
 // You will need to declare a function called toPounds with an appropriately named parameter.
 
 // You should call this function a number of times to check it works for different inputs
+
+let toPounds = function (str) {
+  const penceStringWithoutTrailingP = str.substring(
+    0,
+    penceString.length - 1 // take only 399
+  );
+
+  const paddedPenceNumberString = penceStringWithoutTrailingP.padStart(3, "0"); //The padStart() adds characters to the beginning of a string until the string reaches a specified total length
+
+  const pounds = paddedPenceNumberString.substring(
+    0,
+    paddedPenceNumberString.length - 2 // gives only the pound
+  );
+
+  const pence = paddedPenceNumberString
+    .substring(paddedPenceNumberString.length - 2)
+    .padEnd(2, "0");
+  return `£${pounds}.${pence}`;
+};
+
+const penceString = "399p";
+console.log(toPounds(penceString));
diff --git a/Sprint-2/4-mandatory-interpret/time-format.js b/Sprint-2/4-mandatory-interpret/time-format.js
index 7c98eb0e8..487484f18 100644
--- a/Sprint-2/4-mandatory-interpret/time-format.js
+++ b/Sprint-2/4-mandatory-interpret/time-format.js
@@ -7,7 +7,8 @@ function formatTimeDisplay(seconds) {
   const totalMinutes = (seconds - remainingSeconds) / 60;
   const remainingMinutes = totalMinutes % 60;
   const totalHours = (totalMinutes - remainingMinutes) / 60;
-
+  // console.log(totalHours);
+  console.log(remainingSeconds);
   return `${pad(totalHours)}:${pad(remainingMinutes)}:${pad(remainingSeconds)}`;
 }
 
@@ -17,18 +18,19 @@ function formatTimeDisplay(seconds) {
 // Questions
 
 // a) When formatTimeDisplay is called how many times will pad be called?
-// =============> write your answer here
+// =============> write your answer here ---> 3 times
 
-// Call formatTimeDisplay with an input of 61, now answer the following:
+// Call formatTimeDisplay with an input of 61, now answer the following: ---> 00:01:01
 
 // b) What is the value assigned to num when pad is called for the first time?
-// =============> write your answer here
+// =============> write your answer here ---> 61
 
 // c) What is the return value of pad is called for the first time?
-// =============> write your answer here
+// =============> write your answer here  ---> 0
 
 // d) What is the value assigned to num when pad is called for the last time in this program?  Explain your answer
-// =============> write your answer here
+// =============> write your answer here ---> 1 the function pad is called last time at the last place of return for remainingSeconds
 
 // e) What is the return value assigned to num when pad is called for the last time in this program?  Explain your answer
-// =============> write your answer here
+// =============> write your answer here  --> 1 because num is the parameter and pad has 1 as argument
+console.log(formatTimeDisplay(61));
diff --git a/Sprint-3/1-implement-and-rewrite-tests/implement/1-get-angle-type.js b/Sprint-3/1-implement-and-rewrite-tests/implement/1-get-angle-type.js
index ca1dfe7f2..338645d71 100644
--- a/Sprint-3/1-implement-and-rewrite-tests/implement/1-get-angle-type.js
+++ b/Sprint-3/1-implement-and-rewrite-tests/implement/1-get-angle-type.js
@@ -11,8 +11,8 @@ function getAngleType(angle) {
   if (angle === 90) {
     return "Right angle";
   }
-   // Run the tests, work out what Case 2 is testing, and implement the required code here.
-   // Then keep going for the other cases, one at a time.
+  // Run the tests, work out what Case 2 is testing, and implement the required code here.
+  // Then keep going for the other cases, one at a time.
 }
 
 // The line below allows us to load the getAngleType function into tests in other files.
@@ -27,7 +27,7 @@ function assertEquals(actualOutput, targetOutput) {
     `Expected ${actualOutput} to equal ${targetOutput}`
   );
 }
-
+console.log(90, 180);
 // Acceptance criteria:
 
 // Given an angle in degrees,
@@ -60,4 +60,4 @@ const obtuse = getAngleType(120);
 // Case 5: Identify Reflex Angles:
 // When the angle is greater than 180 degrees and less than 360 degrees,
 // Then the function should return "Reflex angle"
-// ====> write your test here, and then add a line to pass the test in the function above
\ No newline at end of file
+// ====> write your test here, and then add a line to pass the test in the function above
diff --git a/Sprint-3/2-practice-tdd/count.js b/Sprint-3/2-practice-tdd/count.js
index 95b6ebb7d..1a1a7256c 100644
--- a/Sprint-3/2-practice-tdd/count.js
+++ b/Sprint-3/2-practice-tdd/count.js
@@ -1,5 +1,15 @@
 function countChar(stringOfCharacters, findCharacter) {
-  return 5
+  let num = 0;
+  if (findCharacter) {
+    for (let i = 0; i < stringOfCharacters.length; i++) {
+      if (stringOfCharacters[i] === findCharacter) {
+        num++;
+      }
+    }
+    return `${findCharacter} appears ${num} time(s).`;
+  } else return 0;
 }
 
+// console.log(countChar("Hello", "l"));
+
 module.exports = countChar;
diff --git a/Sprint-3/2-practice-tdd/count.test.js b/Sprint-3/2-practice-tdd/count.test.js
index 42baf4b4b..246b08972 100644
--- a/Sprint-3/2-practice-tdd/count.test.js
+++ b/Sprint-3/2-practice-tdd/count.test.js
@@ -22,3 +22,9 @@ test("should count multiple occurrences of a character", () => {
 // And a character char that does not exist within the case-sensitive str,
 // When the function is called with these inputs,
 // Then it should return 0, indicating that no occurrences of the char were found in the case-sensitive str.
+test("should return 0 when a character that does not exist", () => {
+  const str = "aaaaa";
+  const char = "b";
+  const count = countChar(str, char);
+  expect(count).toEqual(0);
+});
diff --git a/Sprint-3/2-practice-tdd/get-ordinal-number.js b/Sprint-3/2-practice-tdd/get-ordinal-number.js
index f95d71db1..7ca87fb73 100644
--- a/Sprint-3/2-practice-tdd/get-ordinal-number.js
+++ b/Sprint-3/2-practice-tdd/get-ordinal-number.js
@@ -1,5 +1,11 @@
 function getOrdinalNumber(num) {
+  if (num > 1 || num < 1) {
+    return "No 1st";
+  }
+
   return "1st";
 }
 
+console.log(getOrdinalNumber(1));
+
 module.exports = getOrdinalNumber;
diff --git a/Sprint-3/2-practice-tdd/repeat.js b/Sprint-3/2-practice-tdd/repeat.js
index 00e60d7f3..d283e2e16 100644
--- a/Sprint-3/2-practice-tdd/repeat.js
+++ b/Sprint-3/2-practice-tdd/repeat.js
@@ -1,5 +1,20 @@
-function repeat() {
-  return "hellohellohello";
+function repeat(str, count) {
+  let repeatedStr = "";
+  if (count < 0) {
+    return "impossible with a negative number";
+  }
+
+  if (count === 0) {
+    return "";
+  }
+  for (i = 1; i <= count; i++) {
+    repeatedStr += str;
+  }
+  return repeatedStr;
 }
 
+/* let test = "hello";
+let c = 3; */
+// console.log(repeat(test, c));
+
 module.exports = repeat;
diff --git a/Sprint-3/2-practice-tdd/repeat.test.js b/Sprint-3/2-practice-tdd/repeat.test.js
index 34097b09c..e86000617 100644
--- a/Sprint-3/2-practice-tdd/repeat.test.js
+++ b/Sprint-3/2-practice-tdd/repeat.test.js
@@ -20,13 +20,31 @@ test("should repeat the string count times", () => {
 // Given a target string str and a count equal to 1,
 // When the repeat function is called with these inputs,
 // Then it should return the original str without repetition, ensuring that a count of 1 results in no repetition.
+test("should return the original string", () => {
+  const str = "hello";
+  const count = 1;
+  const repeatedStr = repeat(str, count);
+  expect(repeatedStr).toEqual("hello");
+});
 
 // case: Handle Count of 0:
 // Given a target string str and a count equal to 0,
 // When the repeat function is called with these inputs,
 // Then it should return an empty string, ensuring that a count of 0 results in an empty output.
+test("should return an empty string when count equal to 0", () => {
+  const str = "hello";
+  const count = 0;
+  const repeatedStr = repeat(str, count);
+  expect(repeatedStr).toEqual("");
+});
 
 // case: Negative Count:
 // Given a target string str and a negative integer count,
 // When the repeat function is called with these inputs,
 // Then it should throw an error or return an appropriate error message, as negative counts are not valid.
+test("should return a message when count a negative number", () => {
+  const str = "hello";
+  const count = -1;
+  const repeatedStr = repeat(str, count);
+  expect(repeatedStr).toEqual("impossible with a negative number");
+});
diff --git a/Sprint-3/3-stretch/cardValidator.js b/Sprint-3/3-stretch/cardValidator.js
new file mode 100644
index 000000000..4101d811b
--- /dev/null
+++ b/Sprint-3/3-stretch/cardValidator.js
@@ -0,0 +1,28 @@
+let cardValidator = function (creditNumber) {
+  let onlyNum = "0123456789";
+  let lastChar = creditNumber[creditNumber.length - 1];
+  let sum = 0;
+  let same = creditNumber[0];
+  if (Number(lastChar) % 2 === 0) {
+    return "error even number at the end";
+  } else {
+    for (let i = 0; i < creditNumber.length; i++) {
+      if (!onlyNum.includes(creditNumber[i])) {
+        return "error on characters";
+      }
+    }
+  }
+  for (let j = 0; j < creditNumber.length; j++) {
+    sum += Number(creditNumber[j]);
+  }
+  if (sum < 16) {
+    return "too short";
+  }
+  for (let g = 1; g < creditNumber.length; g++) {
+    if (same !== creditNumber[g]) {
+      return "It's OK!";
+    }
+  }
+  return "same numbers";
+};
+console.log(cardValidator("7725463"));
diff --git a/Sprint-3/3-stretch/password-validator.js b/Sprint-3/3-stretch/password-validator.js
index b55d527db..d6d42d96d 100644
--- a/Sprint-3/3-stretch/password-validator.js
+++ b/Sprint-3/3-stretch/password-validator.js
@@ -1,6 +1,38 @@
-function passwordValidator(password) {
-    return password.length < 5 ? false : true
-}
+let passwordValidator = function (password) {
+  let digits = password;
+  const integer = "0123456789";
+  let sum = 0;
 
+  for (let i = 0; i < digits.length; i++) {
+    if (!integer.includes(digits[i])) {
+      return "Invalide numbers";
+    }
+  }
 
-module.exports = passwordValidator;
\ No newline at end of file
+  // Check all digits are NOT the same
+  if (digits.split("").every((d) => d === digits[0])) {
+    return "Must not have the same digits";
+  }
+
+  if (digits[digits.length - 1] % 2 !== 0) {
+    return "The last digit must be even";
+  }
+
+  for (let i = 0; i < digits.length; i++) {
+    sum += Number(digits[i]);
+  }
+
+  if (sum <= 16) {
+    return "The sum of all digits must greater than 16";
+  }
+  if (digits.length !== 16) {
+    return "Must have 16 digits";
+  }
+  return "Good one!!";
+};
+
+const test = "4444444444444446";
+console.log(passwordValidator(test));
+// 100% correct without mistakes made by Tam --> to check if all digits are the same, I have to use AI.
+
+module.exports = passwordValidator;