diff --git a/1-exercises/A-undefined/exercise.js b/1-exercises/A-undefined/exercise.js
index 0acfc78d..2e96371f 100644
--- a/1-exercises/A-undefined/exercise.js
+++ b/1-exercises/A-undefined/exercise.js
@@ -12,6 +12,7 @@
 // Example 1
 let a;
 console.log(a);
+//  does not have an assigned value
 
 
 // Example 2
@@ -21,7 +22,7 @@ function sayHello() {
 
 let hello = sayHello();
 console.log(hello);
-
+// a value was not returned
 
 // Example 3
 function sayHelloToUser(user) {
@@ -29,8 +30,9 @@ function sayHelloToUser(user) {
 }
 
 sayHelloToUser();
-
+// there is no any parameter when sayHelloToUser() is called
 
 // Example 4
-let arr = [1,2,3];
+let arr = [1, 2, 3];
 console.log(arr[3]);
+// ther is no value in the arr[3]
\ No newline at end of file
diff --git a/1-exercises/B-while-loop/exercise.js b/1-exercises/B-while-loop/exercise.js
index b459888f..b1a59c65 100644
--- a/1-exercises/B-while-loop/exercise.js
+++ b/1-exercises/B-while-loop/exercise.js
@@ -6,9 +6,14 @@
 */
 
 function evenNumbers(n) {
-    // TODO
+    let i = 0;
+    while (i < n * 2) {
+        console.log(i)
+        i += 2
+    }
 }
 
+
 evenNumbers(3); // should output 0,2,4
 evenNumbers(0); // should output nothing
 evenNumbers(10); // should output 0,2,4,6,8,10,12,14,16,18
diff --git a/1-exercises/C-while-loop-with-array/exercise.js b/1-exercises/C-while-loop-with-array/exercise.js
index d584cd75..e3360012 100644
--- a/1-exercises/C-while-loop-with-array/exercise.js
+++ b/1-exercises/C-while-loop-with-array/exercise.js
@@ -17,7 +17,9 @@ const BIRTHDAYS = [
 ];
 
 function findFirstJulyBDay(birthdays) {
-    // TODO
+    while (BIRTHDAYS.filter(item => item.match(/^July/g))) {
+        return BIRTHDAYS.find(item => item.includes('July'))
+    }
 }
 
 console.log(findFirstJulyBDay(BIRTHDAYS)); // should output "July 11th"
diff --git a/1-exercises/D-do-while/exercise.js b/1-exercises/D-do-while/exercise.js
index f10d0764..57ef5245 100644
--- a/1-exercises/D-do-while/exercise.js
+++ b/1-exercises/D-do-while/exercise.js
@@ -7,9 +7,19 @@
 */
 
 function evenNumbersSum(n) {
-    // TODO
+    let i = 0, j = 0, k = 0
+    if (n !== 0) {
+        do {
+            i += 2
+            k += i
+            j++
+        } while (j < n - 1)
+        return k
+    } else {
+        return 0
+    }
 }
 
 console.log(evenNumbersSum(3)); // should output 6
 console.log(evenNumbersSum(0)); // should output 0
-console.log(evenNumbersSum(10)); // should output 90
\ No newline at end of file
+console.log(evenNumbersSum(10)); // should output 90
diff --git a/1-exercises/E-for-loop/exercise1.js b/1-exercises/E-for-loop/exercise1.js
index db5fac64..63f77dad 100644
--- a/1-exercises/E-for-loop/exercise1.js
+++ b/1-exercises/E-for-loop/exercise1.js
@@ -6,9 +6,8 @@
 
 
 // Change the below code to use a for loop instead of a while loop.
-let i = 0;
-while(i < 26) {
+
+for (let i = 0; i < 26; i++) {
     console.log(String.fromCharCode(97 + i));
-    i++;
 }
 // The output shouldn't change.
diff --git a/1-exercises/E-for-loop/exercise2.js b/1-exercises/E-for-loop/exercise2.js
index 081002b2..b42038c6 100644
--- a/1-exercises/E-for-loop/exercise2.js
+++ b/1-exercises/E-for-loop/exercise2.js
@@ -27,7 +27,9 @@ const AGES = [
 ];
 
 // TODO - Write for loop code here
-
+for (let i = 0; i < WRITERS.length; i++) {
+    console.log(`${WRITERS[i]} is ${AGES[i]} years old`)
+}
 /*
 The output should look something like this:
 
diff --git a/1-exercises/F-for-of-loop/exercise.js b/1-exercises/F-for-of-loop/exercise.js
index 65585c6a..813a02b4 100644
--- a/1-exercises/F-for-of-loop/exercise.js
+++ b/1-exercises/F-for-of-loop/exercise.js
@@ -10,7 +10,12 @@ let tubeStations = [
     "Oxford Street",
     "Tottenham Court Road"
 ];
-
+for (let element of tubeStations) {
+    console.log(element)
+}
 
 // TODO Use a for-of loop to capitalise and output each letter in the string seperately.
 let str = "codeyourfuture";
+for (let s of str) {
+    console.log(s.toUpperCase())
+}
\ No newline at end of file
diff --git a/2-mandatory/1-weather-report.js b/2-mandatory/1-weather-report.js
index dcc2bdb0..f9cc8f67 100644
--- a/2-mandatory/1-weather-report.js
+++ b/2-mandatory/1-weather-report.js
@@ -12,14 +12,18 @@
 */
 
 function getTemperatureReport(cities) {
-    // TODO
+    let arr = []
+    for (let i = 0; i < cities.length; i++) {
+        arr.push(`The temperature in ${cities[i]} is ${temperatureService(cities[i])} degrees`)
+    }
+    return arr
 }
 
 
 /* ======= TESTS - DO NOT MODIFY ===== */
 
 function temperatureService(city) {
-    let temparatureMap  = new Map();
+    let temparatureMap = new Map();
 
     temparatureMap.set('London', 10);
     temparatureMap.set('Paris', 12);
@@ -28,7 +32,7 @@ function temperatureService(city) {
     temparatureMap.set('Mumbai', 29);
     temparatureMap.set('São Paulo', 23);
     temparatureMap.set('Lagos', 33);
-    
+
     return temparatureMap.get(city);
 }
 
diff --git a/2-mandatory/2-retrying-random-numbers.js b/2-mandatory/2-retrying-random-numbers.js
index 10aab37d..eacabcb3 100644
--- a/2-mandatory/2-retrying-random-numbers.js
+++ b/2-mandatory/2-retrying-random-numbers.js
@@ -5,20 +5,24 @@
 
 // This function shouldn't be changed
 function generateRandomNumber() {
-    console.log("Generating number...");
-    return Math.round(Math.random() * 100);
+  console.log('Generating number...');
+  return Math.round(Math.random() * 100);
 }
 
 function getRandomNumberGreaterThan50() {
-    // TODO - implement using a do-while loop
+  let n;
+  do {
+    n = generateRandomNumber();
+  } while (n < 50);
+  return n;
 }
 
 /* ======= TESTS - DO NOT MODIFY ===== */
 
-test("Returned value should always be greater than 50", () => {
-    expect(getRandomNumberGreaterThan50()).toBeGreaterThan(50);
-    expect(getRandomNumberGreaterThan50()).toBeGreaterThan(50);
-    expect(getRandomNumberGreaterThan50()).toBeGreaterThan(50);
-    expect(getRandomNumberGreaterThan50()).toBeGreaterThan(50);
-    expect(getRandomNumberGreaterThan50()).toBeGreaterThan(50);
+test('Returned value should always be greater than 50', () => {
+  expect(getRandomNumberGreaterThan50()).toBeGreaterThan(50);
+  expect(getRandomNumberGreaterThan50()).toBeGreaterThan(50);
+  expect(getRandomNumberGreaterThan50()).toBeGreaterThan(50);
+  expect(getRandomNumberGreaterThan50()).toBeGreaterThan(50);
+  expect(getRandomNumberGreaterThan50()).toBeGreaterThan(50);
 });
diff --git a/2-mandatory/3-financial-times.js b/2-mandatory/3-financial-times.js
index 2ce6fb73..ffaac102 100644
--- a/2-mandatory/3-financial-times.js
+++ b/2-mandatory/3-financial-times.js
@@ -5,7 +5,7 @@
     Implement the function below, which will return a new array containing only article titles which will fit.
 */
 function potentialHeadlines(allArticleTitles) {
-    // TODO
+    return allArticleTitles.filter(item => item.length < 65)
 }
 
 /*
@@ -14,7 +14,11 @@ function potentialHeadlines(allArticleTitles) {
     (you can assume words will always be seperated by a space)
 */
 function titleWithFewestWords(allArticleTitles) {
-    // TODO
+    let wordNums = []
+    for (let i = 0; i < allArticleTitles.length; i++) {
+        wordNums.push(allArticleTitles[i].split(' ').length)
+    }
+    return allArticleTitles[wordNums.indexOf(Math.min(...wordNums))]
 }
 
 /*
@@ -23,7 +27,12 @@ function titleWithFewestWords(allArticleTitles) {
     (Hint: remember that you can also loop through the characters of a string if you need to)
 */
 function headlinesWithNumbers(allArticleTitles) {
-    // TODO
+    let NumberArray = []
+    const regex = /[0-9]/g;
+    for (let i = 0; i < allArticleTitles.length; i++) {
+        if (allArticleTitles[i].search(regex) >= 0) { NumberArray.push(allArticleTitles[i]) }
+    }
+    return NumberArray
 }
 
 /*
@@ -31,7 +40,11 @@ function headlinesWithNumbers(allArticleTitles) {
     Implement the function below to return this number - rounded to the nearest integer.
 */
 function averageNumberOfCharacters(allArticleTitles) {
-    // TODO
+    let sum = 0
+    for (let i = 0; i < allArticleTitles.length; i++) {
+        sum += allArticleTitles[i].length
+    }
+    return Math.round(sum / allArticleTitles.length)
 }
 
 
diff --git a/2-mandatory/4-stocks.js b/2-mandatory/4-stocks.js
index 72d62f94..47e38b80 100644
--- a/2-mandatory/4-stocks.js
+++ b/2-mandatory/4-stocks.js
@@ -34,7 +34,15 @@ const CLOSING_PRICES_LAST_5_DAYS_FOR_ALL_STOCKS = [
         Functions can help with this!
 */
 function getAveragePrices(closingPricesForAllStocks) {
-    // TODO
+    let arr = []
+    for (let i = 0; i < closingPricesForAllStocks.length; i++) {
+        let sum = 0
+        for (let j = 0; j < closingPricesForAllStocks[i].length; j++) {
+            sum += closingPricesForAllStocks[i][j]
+        }
+        arr.push(Number((sum / closingPricesForAllStocks[i].length).toFixed(2)))
+    }
+    return arr
 }
 
 /*
@@ -48,7 +56,15 @@ function getAveragePrices(closingPricesForAllStocks) {
     The price change value should be rounded to 2 decimal places, and should be a number (not a string)
 */
 function getPriceChanges(closingPricesForAllStocks) {
-    // TODO
+    let arr = []
+    for (let i = 0; i < closingPricesForAllStocks.length; i++) {
+        let fiftyDay = closingPricesForAllStocks[i][closingPricesForAllStocks[i].length - 1]
+        let firstDay = closingPricesForAllStocks[i][0]
+        let diffNum = 0
+        diffNum = fiftyDay - firstDay
+        arr.push(Number(diffNum.toFixed(2)))
+    }
+    return arr
 }
 
 /*
@@ -64,7 +80,11 @@ function getPriceChanges(closingPricesForAllStocks) {
     The price should be shown with exactly 2 decimal places.
 */
 function highestPriceDescriptions(closingPricesForAllStocks, stocks) {
-    // TODO
+    let arr = []
+    for (let i = 0; i < closingPricesForAllStocks.length; i++) {
+        arr.push(`The highest price of ${stocks[i].toUpperCase()} in the last 5 days was ${(Math.max(...closingPricesForAllStocks[i])).toFixed(2)}`)
+    }
+    return arr
 }
 
 
diff --git a/3-extra/1-factorial.js b/3-extra/1-factorial.js
index 31f8052c..50e70f8e 100644
--- a/3-extra/1-factorial.js
+++ b/3-extra/1-factorial.js
@@ -9,7 +9,11 @@
 */
 
 function factorial(input) {
-    // TODO
+    let sum = 1
+    for (; input > 0; input--) {
+        sum *= input
+    }
+    return sum
 }
 
 /* ======= TESTS - DO NOT MODIFY ===== */
diff --git a/3-extra/2-array-of-objects.js b/3-extra/2-array-of-objects.js
index ee57960f..b6d7e362 100644
--- a/3-extra/2-array-of-objects.js
+++ b/3-extra/2-array-of-objects.js
@@ -11,72 +11,84 @@
 */
 
 function getHighestRatedInEachGenre(books) {
-    // TODO
+  const result = books.reduce((acc, cur) => {
+    const groupByGenre = cur.genre;
+    if (!acc[groupByGenre]) {
+      acc[groupByGenre] = [];
+    }
+    acc[groupByGenre].push(cur);
+    return acc;
+  }, {});
+  const genreName = Object.keys(result);
+  const arr = [];
+  for (let i = 0; i < genreName.length; i++) {
+    arr.push(result[genreName[i]].sort((a, b) => b.rating - a.rating)[0].title);
+  }
+  return arr;
 }
 
-
 /* ======= Book data - DO NOT MODIFY ===== */
 const BOOKS = [
-    {
-        title: "The Lion, the Witch and the Wardrobe",
-        genre: "children",
-        rating: 4.7
-    },
-    {
-        title: "Sapiens: A Brief History of Humankind",
-        genre: "non-fiction",
-        rating: 4.7
-    },
-    {
-        title: "Nadiya's Fast Flavours",
-        genre: "cooking",
-        rating: 4.7
-    },
-    {
-        title: "Harry Potter and the Philosopher's Stone",
-        genre: "children",
-        rating: 4.8
-    },
-    {
-        title: "A Life on Our Planet",
-        genre: "non-fiction",
-        rating: 4.8
-    },
-    {
-        title: "Dishoom: The first ever cookbook from the much-loved Indian restaurant",
-        genre: "cooking",
-        rating: 4.85
-    },
-    {
-        title: "Gangsta Granny Strikes Again!",
-        genre: "children",
-        rating: 4.9
-    },
-    {
-        title: "Diary of a Wimpy Kid",
-        genre: "children",
-        rating: 4.6
-    },
-    {
-        title: "BOSH!: Simple recipes. Unbelievable results. All plants.",
-        genre: "cooking",
-        rating: 4.6
-    },
-    {
-        title: "The Book Your Dog Wishes You Would Read",
-        genre: "non-fiction",
-        rating: 4.85
-    },
-]
-
+  {
+    title: 'The Lion, the Witch and the Wardrobe',
+    genre: 'children',
+    rating: 4.7
+  },
+  {
+    title: 'Sapiens: A Brief History of Humankind',
+    genre: 'non-fiction',
+    rating: 4.7
+  },
+  {
+    title: "Nadiya's Fast Flavours",
+    genre: 'cooking',
+    rating: 4.7
+  },
+  {
+    title: "Harry Potter and the Philosopher's Stone",
+    genre: 'children',
+    rating: 4.8
+  },
+  {
+    title: 'A Life on Our Planet',
+    genre: 'non-fiction',
+    rating: 4.8
+  },
+  {
+    title:
+      'Dishoom: The first ever cookbook from the much-loved Indian restaurant',
+    genre: 'cooking',
+    rating: 4.85
+  },
+  {
+    title: 'Gangsta Granny Strikes Again!',
+    genre: 'children',
+    rating: 4.9
+  },
+  {
+    title: 'Diary of a Wimpy Kid',
+    genre: 'children',
+    rating: 4.6
+  },
+  {
+    title: 'BOSH!: Simple recipes. Unbelievable results. All plants.',
+    genre: 'cooking',
+    rating: 4.6
+  },
+  {
+    title: 'The Book Your Dog Wishes You Would Read',
+    genre: 'non-fiction',
+    rating: 4.85
+  }
+];
 
 /* ======= TESTS - DO NOT MODIFY ===== */
-test("should return the highest rated book in each genre", () => {
-    expect(new Set(getHighestRatedInEachGenre(BOOKS))).toEqual(new Set(
-        [
-            "The Book Your Dog Wishes You Would Read",
-            "Gangsta Granny Strikes Again!",
-            "Dishoom: The first ever cookbook from the much-loved Indian restaurant"
-        ]
-    ));
-});
\ No newline at end of file
+test('should return the highest rated book in each genre', () => {
+  expect(new Set(getHighestRatedInEachGenre(BOOKS))).toEqual(
+    new Set([
+      'The Book Your Dog Wishes You Would Read',
+      'Gangsta Granny Strikes Again!',
+      'Dishoom: The first ever cookbook from the much-loved Indian restaurant'
+    ])
+  );
+});
diff --git a/3-extra/3-fibonacci.js b/3-extra/3-fibonacci.js
index 9ef9aec7..33291fb7 100644
--- a/3-extra/3-fibonacci.js
+++ b/3-extra/3-fibonacci.js
@@ -14,7 +14,12 @@
 */
 
 function generateFibonacciSequence(n) {
-    // TODO
+    let arr = []
+    const firstSecondNum = [0, 1]
+    for (let i = 0; i < n; i++) {
+        i === 0 || i === 1 ? arr.push(firstSecondNum[i]) : arr.push(arr[i - 2] + arr[i - 1])
+    }
+    return arr
 }
 
 /* ======= TESTS - DO NOT MODIFY ===== */