diff --git a/1-exercises/A-undefined/exercise.js b/1-exercises/A-undefined/exercise.js
index 0acfc78d..2ddb8021 100644
--- a/1-exercises/A-undefined/exercise.js
+++ b/1-exercises/A-undefined/exercise.js
@@ -9,12 +9,12 @@
     For each example, can you explain why we are seeing undefined?
 */
 
-// Example 1
+// Example 1: because no value assign to the variable "a"
 let a;
 console.log(a);
 
 
-// Example 2
+// Example 2: because function does not have any return. 
 function sayHello() {
     let message = "Hello";
 }
@@ -23,7 +23,7 @@ let hello = sayHello();
 console.log(hello);
 
 
-// Example 3
+// Example 3: because there is no argument when call the function.
 function sayHelloToUser(user) {
     console.log(`Hello ${user}`);
 }
@@ -31,6 +31,6 @@ function sayHelloToUser(user) {
 sayHelloToUser();
 
 
-// Example 4
+// Example 4: because arr[3] dose not have value.
 let arr = [1,2,3];
 console.log(arr[3]);
diff --git a/1-exercises/B-while-loop/exercise.js b/1-exercises/B-while-loop/exercise.js
index b459888f..7cb80908 100644
--- a/1-exercises/B-while-loop/exercise.js
+++ b/1-exercises/B-while-loop/exercise.js
@@ -7,6 +7,16 @@
 
 function evenNumbers(n) {
     // TODO
+    let i=0;
+    let evenNumber = 0;
+    let arr = [];
+    while(i<n){
+        evenNumber = i*2;        
+        arr[i] = evenNumber;        
+        i++;        
+    }
+    let commaSeperated = arr.join(",");
+    console.log(commaSeperated);
 }
 
 evenNumbers(3); // should output 0,2,4
diff --git a/1-exercises/C-while-loop-with-array/exercise.js b/1-exercises/C-while-loop-with-array/exercise.js
index d584cd75..0a0db841 100644
--- a/1-exercises/C-while-loop-with-array/exercise.js
+++ b/1-exercises/C-while-loop-with-array/exercise.js
@@ -1,3 +1,4 @@
+
 /*
     Loops can be useful when working with arrays.
     In the below example, imagine we've defined an array holding the birthdays of your closest friends.
@@ -18,6 +19,13 @@ const BIRTHDAYS = [
 
 function findFirstJulyBDay(birthdays) {
     // TODO
+    let i=0;
+    while(!(birthdays[i].includes("July"))){
+        
+        i++;
+    }
+    return birthdays[i];
+
 }
 
 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..a13eb357 100644
--- a/1-exercises/D-do-while/exercise.js
+++ b/1-exercises/D-do-while/exercise.js
@@ -8,6 +8,16 @@
 
 function evenNumbersSum(n) {
     // TODO
+    let i=0;
+    let sumEven=0;
+    do{
+        sumEven+=(i*2)
+        i++;
+    }
+    while ( i<n);
+
+    return (sumEven);
+
 }
 
 console.log(evenNumbersSum(3)); // should output 6
diff --git a/1-exercises/E-for-loop/exercise1.js b/1-exercises/E-for-loop/exercise1.js
index db5fac64..a575d50c 100644
--- a/1-exercises/E-for-loop/exercise1.js
+++ b/1-exercises/E-for-loop/exercise1.js
@@ -6,9 +6,9 @@
 
 
 // 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..41edec33 100644
--- a/1-exercises/E-for-loop/exercise2.js
+++ b/1-exercises/E-for-loop/exercise2.js
@@ -27,6 +27,9 @@ const AGES = [
 ];
 
 // TODO - Write for loop code here
+for (let i=0;i<WRITERS.length-1;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..b8a77d3b 100644
--- a/1-exercises/F-for-of-loop/exercise.js
+++ b/1-exercises/F-for-of-loop/exercise.js
@@ -10,7 +10,13 @@ let tubeStations = [
     "Oxford Street",
     "Tottenham Court Road"
 ];
+for (let tubeStation of tubeStations){
+    console.log (tubeStation)
+}
 
 
 // TODO Use a for-of loop to capitalise and output each letter in the string seperately.
 let str = "codeyourfuture";
+for( char of str){
+    console.log (char.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..e125890f 100644
--- a/2-mandatory/1-weather-report.js
+++ b/2-mandatory/1-weather-report.js
@@ -13,6 +13,12 @@
 
 function getTemperatureReport(cities) {
     // TODO
+    let arr=[];    
+    for (let citi of cities)  {     
+         arr.push(`The temperature in ${citi} is ${temperatureService(citi)} degrees`);
+        
+    }
+    return arr;
 }
 
 
diff --git a/2-mandatory/2-retrying-random-numbers.js b/2-mandatory/2-retrying-random-numbers.js
index 10aab37d..7a60b49b 100644
--- a/2-mandatory/2-retrying-random-numbers.js
+++ b/2-mandatory/2-retrying-random-numbers.js
@@ -11,6 +11,11 @@ function generateRandomNumber() {
 
 function getRandomNumberGreaterThan50() {
     // TODO - implement using a do-while loop
+    let value= 0;
+    do{
+        value = generateRandomNumber();
+    }while (value < 50);
+    return value;
 }
 
 /* ======= TESTS - DO NOT MODIFY ===== */
diff --git a/2-mandatory/3-financial-times.js b/2-mandatory/3-financial-times.js
index 2ce6fb73..8c55c155 100644
--- a/2-mandatory/3-financial-times.js
+++ b/2-mandatory/3-financial-times.js
@@ -6,6 +6,13 @@
 */
 function potentialHeadlines(allArticleTitles) {
     // TODO
+    let arr =[];
+    for (let article of allArticleTitles){
+        if (article.length <= 65){
+            arr.push(article)
+        }
+    }
+    return arr;
 }
 
 /*
@@ -15,6 +22,16 @@ function potentialHeadlines(allArticleTitles) {
 */
 function titleWithFewestWords(allArticleTitles) {
     // TODO
+        
+    let arr =[];
+    myMin= 0;
+    
+    for (let article of allArticleTitles){
+        arr.push (article.split(' ').length);  
+    }
+    
+    myMin= Math.min(...arr);
+    return allArticleTitles[arr.indexOf(myMin)];
 }
 
 /*
@@ -24,6 +41,18 @@ function titleWithFewestWords(allArticleTitles) {
 */
 function headlinesWithNumbers(allArticleTitles) {
     // TODO
+    let arr=[]
+    for (let article of allArticleTitles){
+        for (let char of article){
+            if (char>="0" && char<="9"){
+                arr.push (article);
+                break;
+            }
+
+        }
+    }
+    return arr
+
 }
 
 /*
@@ -32,6 +61,12 @@ function headlinesWithNumbers(allArticleTitles) {
 */
 function averageNumberOfCharacters(allArticleTitles) {
     // TODO
+    let sum=0;
+    for (let article of allArticleTitles){
+        sum+=article.length;
+    }
+    return Math.round(sum/allArticleTitles.length)
+
 }
 
 
diff --git a/2-mandatory/4-stocks.js b/2-mandatory/4-stocks.js
index 72d62f94..038de7e4 100644
--- a/2-mandatory/4-stocks.js
+++ b/2-mandatory/4-stocks.js
@@ -33,8 +33,20 @@ const CLOSING_PRICES_LAST_5_DAYS_FOR_ALL_STOCKS = [
         Solve the smaller problems, and then build those solutions back up to solve the larger problem.
         Functions can help with this!
 */
-function getAveragePrices(closingPricesForAllStocks) {
-    // TODO
+ function getAveragePrices(closingPricesForAllStocks) {
+    // TODOfunction
+    
+    let averageArr=[];
+    for (let closingPricesForStock of closingPricesForAllStocks){
+        let sum =0;
+        for (let item of closingPricesForStock){
+            sum=sum+item;
+        }
+        averageArr.push(Number((sum/closingPricesForStock.length).toFixed(2)));
+        
+    }
+    return averageArr;
+
 }
 
 /*
@@ -48,10 +60,17 @@ 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
+   // TODO
+   let arr=[];
+   for (let closingPricesForStock of closingPricesForAllStocks){    
+    arr.push(Number((closingPricesForStock[closingPricesForStock.length-1]-closingPricesForStock[0]).toFixed(2)));
+    
+   }
+   return arr;
+   
 }
 
-/*
+   /*
     As part of a financial report, we want to see what the highest price was for each stock in the last 5 days.
     Implement the below function, which
         - Takes 2 parameters:
@@ -63,8 +82,15 @@ function getPriceChanges(closingPricesForAllStocks) {
     The stock ticker should be capitalised.
     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..ba58ee03 100644
--- a/3-extra/1-factorial.js
+++ b/3-extra/1-factorial.js
@@ -10,6 +10,13 @@
 
 function factorial(input) {
     // TODO
+    let i=1;
+    let multy=1;
+    while(i<= input){
+        multy*=i;
+        i++;
+    }
+    return multy;
 }
 
 /* ======= TESTS - DO NOT MODIFY ===== */
diff --git a/3-extra/2-array-of-objects.js b/3-extra/2-array-of-objects.js
index ee57960f..0ee4a4c9 100644
--- a/3-extra/2-array-of-objects.js
+++ b/3-extra/2-array-of-objects.js
@@ -11,72 +11,97 @@
 */
 
 function getHighestRatedInEachGenre(books) {
-    // TODO
-}
+  // TODO
+  let child = [];
+  let scFiction = [];
+  let cook = [];
+  resultArr = [];
+  for (let i = 0; i < books.length; i++) {
+    if (books[i].genre === "children") {
+      child.push(books[i]);
+    } else if (books[i].genre === "cooking") {
+      cook.push(books[i]);
+    } else {
+      // console.log("helllo");
+      scFiction.push(books[i]);
+    }
+  }
+  console.log(scFiction, child, cook);
+
+  let scFictionSorted = scFiction.sort((a, b) => a.rating - b.rating);
+  let childSorted = child.sort((a, b) => a.rating - b.rating);
+
+  let cookSorted = cook.sort((a, b) => a.rating - b.rating);
 
+  resultArr.push(scFictionSorted[scFictionSorted.length - 1].title);
+  resultArr.push(childSorted[childSorted.length - 1].title);
+  resultArr.push(cookSorted[cookSorted.length - 1].title);
+
+  return resultArr;
+}
 
 /* ======= 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
+  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..427297e9 100644
--- a/3-extra/3-fibonacci.js
+++ b/3-extra/3-fibonacci.js
@@ -14,7 +14,13 @@
 */
 
 function generateFibonacciSequence(n) {
-    // TODO
+    // TODo
+    let arr=[0,1];
+    for (let i=0;i<n-2;i++){
+        arr.push (arr[i]+arr[i+1]);
+    }           
+    
+    return arr;
 }
 
 /* ======= TESTS - DO NOT MODIFY ===== */