diff --git a/1-exercises/A-undefined/exercise.js b/1-exercises/A-undefined/exercise.js
index 0acfc78d..14ad45b1 100644
--- a/1-exercises/A-undefined/exercise.js
+++ b/1-exercises/A-undefined/exercise.js
@@ -12,13 +12,13 @@
 // Example 1
 let a;
 console.log(a);
-
+// The variable is not assigned to any value.
 
 // Example 2
 function sayHello() {
     let message = "Hello";
 }
-
+//function doesn't return a value 
 let hello = sayHello();
 console.log(hello);
 
@@ -29,8 +29,9 @@ function sayHelloToUser(user) {
 }
 
 sayHelloToUser();
-
+// when function called to argument has given.
 
 // Example 4
 let arr = [1,2,3];
 console.log(arr[3]);
+// there is only 0,1,2 index in this array only.
diff --git a/1-exercises/B-while-loop/exercise.js b/1-exercises/B-while-loop/exercise.js
index b459888f..1ed791cd 100644
--- a/1-exercises/B-while-loop/exercise.js
+++ b/1-exercises/B-while-loop/exercise.js
@@ -7,6 +7,14 @@
 
 function evenNumbers(n) {
     // TODO
+let i = 0;
+let st = "";
+while (i < n * 2 && i % 2 === 0){
+  st+=i
+  
+  i+=2
+}
+console.log(st)
 }
 
 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..426e5b5b 100644
--- a/1-exercises/C-while-loop-with-array/exercise.js
+++ b/1-exercises/C-while-loop-with-array/exercise.js
@@ -18,6 +18,11 @@ const BIRTHDAYS = [
 
 function findFirstJulyBDay(birthdays) {
     // TODO
+    let i = 0;
+    while (i < birthdays.length) {
+      if (birthdays[i].startsWith("July")) return birthdays[i];
+      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..c82b499b 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 sum = 0;
+    do {
+     if (i % 2 === 0) {
+     sum += i;   
+     }
+     i++
+    }
+    while (i < n * 2);
+return sum;
 }
 
 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..08aee244 100644
--- a/1-exercises/E-for-loop/exercise1.js
+++ b/1-exercises/E-for-loop/exercise1.js
@@ -6,9 +6,12 @@
 
 
 // Change the below code to use a for loop instead of a while loop.
-let i = 0;
-while(i < 26) {
-    console.log(String.fromCharCode(97 + i));
-    i++;
+for (let i = 0; i < 26 ; i++) {
+console.log(String.fromCharCode(97 + i));
 }
+// let i = 0;
+// while(i < 26) {
+//     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..afe6af32 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; 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..a7dcb865 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 (const 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 (const element of str) {
+    console.log(element.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..f1fe3154 100644
--- a/2-mandatory/1-weather-report.js
+++ b/2-mandatory/1-weather-report.js
@@ -13,6 +13,11 @@
 
 function getTemperatureReport(cities) {
     // TODO
+    let report = [];
+    for (let i = 0; i < cities.length; i++) {
+      report[i] = `The temperature in ${cities[i]} is ${temperatureService(cities[i])} degrees`;
+    }
+    return report;
 }
 
 
diff --git a/2-mandatory/2-retrying-random-numbers.js b/2-mandatory/2-retrying-random-numbers.js
index 10aab37d..4338f365 100644
--- a/2-mandatory/2-retrying-random-numbers.js
+++ b/2-mandatory/2-retrying-random-numbers.js
@@ -11,6 +11,12 @@ function generateRandomNumber() {
 
 function getRandomNumberGreaterThan50() {
     // TODO - implement using a do-while loop
+    let counter = 0; 
+    do {
+    counter = generateRandomNumber();
+    } while ( counter<=50);
+    return counter;
+    
 }
 
 /* ======= TESTS - DO NOT MODIFY ===== */
diff --git a/2-mandatory/3-financial-times.js b/2-mandatory/3-financial-times.js
index 2ce6fb73..024bb3ad 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(title => title.length <= 65);  
 }
 
 /*
@@ -14,7 +14,14 @@ function potentialHeadlines(allArticleTitles) {
     (you can assume words will always be seperated by a space)
 */
 function titleWithFewestWords(allArticleTitles) {
-    // TODO
+    let shortestTitle = allArticleTitles[0];
+
+    allArticleTitles.forEach(title => {
+        if (title.length < shortestTitle.length) {
+            shortestTitle = title
+        }
+    })
+    return shortestTitle
 }
 
 /*
@@ -23,7 +30,10 @@ function titleWithFewestWords(allArticleTitles) {
     (Hint: remember that you can also loop through the characters of a string if you need to)
 */
 function headlinesWithNumbers(allArticleTitles) {
-    // TODO
+    return allArticleTitles.filter(title => {
+      const numbersInTitle = title.match(/[1-9]/g)
+      return numbersInTitle != null ? true : false
+    })
 }
 
 /*
@@ -31,7 +41,11 @@ function headlinesWithNumbers(allArticleTitles) {
     Implement the function below to return this number - rounded to the nearest integer.
 */
 function averageNumberOfCharacters(allArticleTitles) {
-    // TODO
+    const articleTitleLengths = allArticleTitles.map(title => title.length)
+
+    const sumOfTitleLengths = articleTitleLengths.reduce(function(partialSum, a) {return partialSum + a}, 0)
+  
+    return Math.round(sumOfTitleLengths / allArticleTitles.length)
 }
 
 
diff --git a/2-mandatory/4-stocks.js b/2-mandatory/4-stocks.js
index 72d62f94..763129c0 100644
--- a/2-mandatory/4-stocks.js
+++ b/2-mandatory/4-stocks.js
@@ -34,7 +34,11 @@ const CLOSING_PRICES_LAST_5_DAYS_FOR_ALL_STOCKS = [
         Functions can help with this!
 */
 function getAveragePrices(closingPricesForAllStocks) {
-    // TODO
+    return closingPricesForAllStocks.map(stockPrices => {
+        const sumOfStockPrices = stockPrices.reduce(function(partialSum, a) {return partialSum + a}, 0)
+  
+    return Number((sumOfStockPrices / stockPrices.length).toFixed(2));
+      })
 }
 
 /*
@@ -48,7 +52,9 @@ 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
+    return closingPricesForAllStocks.map(prices => {
+        return Number((prices[prices.length -1] - prices[0]).toFixed(2));
+      })
 }
 
 /*
@@ -64,7 +70,14 @@ function getPriceChanges(closingPricesForAllStocks) {
     The price should be shown with exactly 2 decimal places.
 */
 function highestPriceDescriptions(closingPricesForAllStocks, stocks) {
-    // TODO
+        const highestPrices = []
+        
+        for (let i = 0; i < closingPricesForAllStocks.length; i++){
+          const maxPrice = Math.max(...closingPricesForAllStocks[i])
+          highestPrices.push(`The highest price of ${stocks[i].toUpperCase()} in the last 5 days was ${maxPrice.toFixed(2)}`)
+        }
+      
+        return highestPrices
 }
 
 
diff --git a/3-extra/1-factorial.js b/3-extra/1-factorial.js
index 31f8052c..0daab393 100644
--- a/3-extra/1-factorial.js
+++ b/3-extra/1-factorial.js
@@ -10,9 +10,14 @@
 
 function factorial(input) {
     // TODO
-}
+	let factorial = input;
 
-/* ======= TESTS - DO NOT MODIFY ===== */
+	for (let i = input-1; i > 1; i--) {
+		factorial *= i;
+	}
+	return factorial;
+}
+// /* ======= TESTS - DO NOT MODIFY ===== */
 
 test("3! should be 6", () => {
     expect(factorial(3)).toEqual(6);