diff --git a/src/functions-and-arrays.js b/src/functions-and-arrays.js
index 3a7dbec41..5bdbe6ef3 100644
--- a/src/functions-and-arrays.js
+++ b/src/functions-and-arrays.js
@@ -1,24 +1,49 @@
 // Iteration #1: Find the maximum
-function maxOfTwoNumbers() {}
+function maxOfTwoNumbers(num1, num2) {
+  return num1 > num2? num1 : num2;
+}
 
 
 
 // Iteration #2: Find longest word
 const words = ['mystery', 'brother', 'aviator', 'crocodile', 'pearl', 'orchard', 'crackpot'];
 
-function findLongestWord() {}
-
+function findLongestWord() {
+  let longestWord = '';
+  for (let i = 0; i < words.length; i++) {
+      if (words[i].length > longestWord.length) {
+          longestWord = words[i];
+      }
+  }
+  return longestWord;
+}
 
 
 // Iteration #3: Calculate the sum
 const numbers = [6, 12, 1, 18, 13, 16, 2, 1, 8, 10];
 
-function sumNumbers() {}
+function sumNumbers() {
+  let sum = 0;
+  for (let i = 0; i < numbers.length; i++) {
+      sum += numbers[i];
+  }
+  return sum;
+}
 
 
 
 // Iteration #3.1 Bonus:
-function sum() {}
+const mixedArr = [6, 12, 'miami', 1, true, 'barca', '200', 'lisboa', 8, 10];
+
+function sum() {
+  let sum = 0;
+  for (let i = 0; i < mixedArr.length; i++) {
+      if (typeof mixedArr[i] === 'number' && typeof (mixedArr[i]) === "string") {	    
+          sum += mixedArr[i];
+      }
+  }
+  return sum;
+}
 
 
 
@@ -26,87 +51,140 @@ function sum() {}
 // Level 1: Array of numbers
 const numbersAvg = [2, 6, 9, 10, 7, 4, 1, 9];
 
-function averageNumbers() {}
+function averageNumbers() {
+  let sum = 0;
+  for (let i = 0; i < numbersAvg.length; i++) {
+      sum += numbersAvg[i];
+  }
+  return sum / numbersAvg.length;
+}
 
 
 // Level 2: Array of strings
 const wordsArr = ['seat', 'correspond', 'linen', 'motif', 'hole', 'smell', 'smart', 'chaos', 'fuel', 'palace'];
 
-function averageWordLength() { }
+function averageWordLength() { 
+  let sum = 0;
+  for (let i = 0; i < wordsArr.length; i++) {
+      sum += wordsArr[i].length;
+  }
+  return sum / wordsArr.length;
+}
 
 // Bonus - Iteration #4.1
-function avg() {}
+const mixedArray = [6, 12, 'miami', 1, true, 'barca', '200', 'lisboa', 8, 10];
+
+function avg() {
+  let sum = 0;
+  for (let i = 0; i < mixedArray.length; i++) {
+      if (typeof mixedArray[i] === 'number' && typeof (mixedArray[i]) === "string") {
+          sum += mixedArray[i];
+      }
+  }
+  return sum / mixedArray.length;
+}
 
 // Iteration #5: Unique arrays
 const wordsUnique = [
-  'crab',
-  'poison',
-  'contagious',
-  'simple',
-  'bring',
-  'sharp',
-  'playground',
-  'poison',
-  'communion',
-  'simple',
-  'bring'
+'crab',
+'poison',
+'contagious',
+'simple',
+'bring',
+'sharp',
+'playground',
+'poison',
+'communion',
+'simple',
+'bring'
 ];
 
-function uniquifyArray() {}
+function uniquifyArray() {
+  let uniqueArray = [];
+  for (let i = 0; i < wordsUnique.length; i++) {
+      if (!uniqueArray.includes(wordsUnique[i])) {
+          uniqueArray.push(wordsUnique[i]);
+      }
+  }
+  return uniqueArray;
+}
 
 
 
 // Iteration #6: Find elements
 const wordsFind = ['machine', 'subset', 'trouble', 'starting', 'matter', 'eating', 'truth', 'disobedience'];
 
-function doesWordExist() {}
-
+function doesWordExist(word) {
+  return wordsFind.includes(word);
+}
 
 
 // Iteration #7: Count repetition
 const wordsCount = [
-  'machine',
-  'matter',
-  'subset',
-  'trouble',
-  'starting',
-  'matter',
-  'eating',
-  'matter',
-  'truth',
-  'disobedience',
-  'matter'
+'machine',
+'matter',
+'subset',
+'trouble',
+'starting',
+'matter',
+'eating',
+'matter',
+'truth',
+'disobedience',
+'matter'
 ];
 
-function howManyTimes() {}
+function howManyTimes(times) {
+  let count = 0;
+  for (let i = 0; i < wordsCount.length; i++) {
+      if (wordsCount[i] === times) {
+          count++;
+      }
+  }
+  return count;
+} 
 
 
 
 // Iteration #8: Bonus
 const matrix = [
-  [8, 2, 22, 97, 38, 15, 0, 40, 0, 75, 4, 5, 7, 78, 52, 12, 50, 77, 91, 8],
-  [49, 49, 99, 40, 17, 81, 18, 57, 60, 87, 17, 40, 98, 43, 69, 48, 4, 56, 62, 0],
-  [81, 49, 31, 73, 55, 79, 14, 29, 93, 71, 40, 67, 53, 88, 30, 3, 49, 13, 36, 65],
-  [52, 70, 95, 23, 4, 60, 11, 42, 69, 24, 68, 56, 1, 32, 56, 71, 37, 2, 36, 91],
-  [22, 31, 16, 71, 51, 67, 63, 89, 41, 92, 36, 54, 22, 40, 40, 28, 66, 33, 13, 80],
-  [24, 47, 32, 60, 99, 3, 45, 2, 44, 75, 33, 53, 78, 36, 84, 20, 35, 17, 12, 50],
-  [32, 98, 81, 28, 64, 23, 67, 10, 26, 38, 40, 67, 59, 54, 70, 66, 18, 38, 64, 70],
-  [67, 26, 20, 68, 2, 62, 12, 20, 95, 63, 94, 39, 63, 8, 40, 91, 66, 49, 94, 21],
-  [24, 55, 58, 5, 66, 73, 99, 26, 97, 17, 78, 78, 96, 83, 14, 88, 34, 89, 63, 72],
-  [21, 36, 23, 9, 75, 0, 76, 44, 20, 45, 35, 14, 0, 61, 33, 97, 34, 31, 33, 95],
-  [78, 17, 53, 28, 22, 75, 31, 67, 15, 94, 3, 80, 4, 62, 16, 14, 9, 53, 56, 92],
-  [16, 39, 5, 42, 96, 35, 31, 47, 55, 58, 88, 24, 0, 17, 54, 24, 36, 29, 85, 57],
-  [86, 56, 0, 48, 35, 71, 89, 7, 5, 44, 44, 37, 44, 60, 21, 58, 51, 54, 17, 58],
-  [19, 80, 81, 68, 5, 94, 47, 69, 28, 73, 92, 13, 86, 52, 17, 77, 4, 89, 55, 40],
-  [4, 52, 8, 83, 97, 35, 99, 16, 7, 97, 57, 32, 16, 26, 26, 79, 33, 27, 98, 66],
-  [88, 36, 68, 87, 57, 62, 20, 72, 3, 46, 33, 67, 46, 55, 12, 32, 63, 93, 53, 69],
-  [4, 42, 16, 73, 38, 25, 39, 11, 24, 94, 72, 18, 8, 46, 29, 32, 40, 62, 76, 36],
-  [20, 69, 36, 41, 72, 30, 23, 88, 34, 62, 99, 69, 82, 67, 59, 85, 74, 4, 36, 16],
-  [20, 73, 35, 29, 78, 31, 90, 1, 74, 31, 49, 71, 48, 86, 81, 16, 23, 57, 5, 54],
-  [1, 70, 54, 71, 83, 51, 54, 69, 16, 92, 33, 48, 61, 43, 52, 1, 89, 19, 67, 48]
+[8, 2, 22, 97, 38, 15, 0, 40, 0, 75, 4, 5, 7, 78, 52, 12, 50, 77, 91, 8],
+[49, 49, 99, 40, 17, 81, 18, 57, 60, 87, 17, 40, 98, 43, 69, 48, 4, 56, 62, 0],
+[81, 49, 31, 73, 55, 79, 14, 29, 93, 71, 40, 67, 53, 88, 30, 3, 49, 13, 36, 65],
+[52, 70, 95, 23, 4, 60, 11, 42, 69, 24, 68, 56, 1, 32, 56, 71, 37, 2, 36, 91],
+[22, 31, 16, 71, 51, 67, 63, 89, 41, 92, 36, 54, 22, 40, 40, 28, 66, 33, 13, 80],
+[24, 47, 32, 60, 99, 3, 45, 2, 44, 75, 33, 53, 78, 36, 84, 20, 35, 17, 12, 50],
+[32, 98, 81, 28, 64, 23, 67, 10, 26, 38, 40, 67, 59, 54, 70, 66, 18, 38, 64, 70],
+[67, 26, 20, 68, 2, 62, 12, 20, 95, 63, 94, 39, 63, 8, 40, 91, 66, 49, 94, 21],
+[24, 55, 58, 5, 66, 73, 99, 26, 97, 17, 78, 78, 96, 83, 14, 88, 34, 89, 63, 72],
+[21, 36, 23, 9, 75, 0, 76, 44, 20, 45, 35, 14, 0, 61, 33, 97, 34, 31, 33, 95],
+[78, 17, 53, 28, 22, 75, 31, 67, 15, 94, 3, 80, 4, 62, 16, 14, 9, 53, 56, 92],
+[16, 39, 5, 42, 96, 35, 31, 47, 55, 58, 88, 24, 0, 17, 54, 24, 36, 29, 85, 57],
+[86, 56, 0, 48, 35, 71, 89, 7, 5, 44, 44, 37, 44, 60, 21, 58, 51, 54, 17, 58],
+[19, 80, 81, 68, 5, 94, 47, 69, 28, 73, 92, 13, 86, 52, 17, 77, 4, 89, 55, 40],
+[4, 52, 8, 83, 97, 35, 99, 16, 7, 97, 57, 32, 16, 26, 26, 79, 33, 27, 98, 66],
+[88, 36, 68, 87, 57, 62, 20, 72, 3, 46, 33, 67, 46, 55, 12, 32, 63, 93, 53, 69],
+[4, 42, 16, 73, 38, 25, 39, 11, 24, 94, 72, 18, 8, 46, 29, 32, 40, 62, 76, 36],
+[20, 69, 36, 41, 72, 30, 23, 88, 34, 62, 99, 69, 82, 67, 59, 85, 74, 4, 36, 16],
+[20, 73, 35, 29, 78, 31, 90, 1, 74, 31, 49, 71, 48, 86, 81, 16, 23, 57, 5, 54],
+[1, 70, 54, 71, 83, 51, 54, 69, 16, 92, 33, 48, 61, 43, 52, 1, 89, 19, 67, 48]
 ];
 
-function greatestProduct() {}
+function greatestProduct() {
+  let maxProduct = 0;
+  for (let i = 0; i < matrix.length; i++) {
+      for (let j = 0; j < matrix[i].length; j++) {
+          let product = 1;
+          for (let k = j; k < j + 4; k++) {
+              product *= matrix[i][k];
+          }
+          if (product > maxProduct) {
+              maxProduct = product;
+          }
+      }
+  }
+  return maxProduct;
+}
 
 
 
@@ -114,17 +192,17 @@ function greatestProduct() {}
 // The following is required to make unit tests work.
 /* Environment setup. Do not modify the below code. */
 if (typeof module !== 'undefined') {
-  module.exports = {
-    maxOfTwoNumbers,
-    findLongestWord,
-    sumNumbers,
-    sum,
-    averageNumbers,
-    averageWordLength,
-    avg,
-    uniquifyArray,
-    doesWordExist,
-    howManyTimes,
-    greatestProduct
-  };
+module.exports = {
+  maxOfTwoNumbers,
+  findLongestWord,
+  sumNumbers,
+  sum,
+  averageNumbers,
+  averageWordLength,
+  avg,
+  uniquifyArray,
+  doesWordExist,
+  howManyTimes,
+  greatestProduct
+};
 }