diff --git a/src/functions-and-arrays.js b/src/functions-and-arrays.js
index 3a7dbec..bf1d86b 100644
--- a/src/functions-and-arrays.js
+++ b/src/functions-and-arrays.js
@@ -1,41 +1,109 @@
 // Iteration #1: Find the maximum
-function maxOfTwoNumbers() {}
-
+function maxOfTwoNumbers(num1, num2) {
+  if (num1 > num2) {
+    return num1;
+  } else {
+    return num2;
+  }
+}
 
 
 // Iteration #2: Find longest word
 const words = ['mystery', 'brother', 'aviator', 'crocodile', 'pearl', 'orchard', 'crackpot'];
 
-function findLongestWord() {}
+function findLongestWord(words) {
+  if (words.length === 0) return null;
+
+  let longest = words[0];
+
+  for (let i = 1; i < words.length; i++) {
+    if (words[i].length > longest.length) {
+      longest = words[i];
+    }
+  }
 
+  return longest;
+}
 
 
 // Iteration #3: Calculate the sum
 const numbers = [6, 12, 1, 18, 13, 16, 2, 1, 8, 10];
 
-function sumNumbers() {}
+function sumNumbers(numbers) {
+  let sum = 0;
+
+  for (let i = 0; i < numbers.length; i++) {
+    sum += numbers[i];
+  }
 
+  return sum;
+}
 
 
 // Iteration #3.1 Bonus:
-function sum() {}
-
+function sum(arr) {
+  let total = 0;
+
+  for (let i = 0; i < arr.length; i++) {
+    if (typeof arr[i] === 'number') {
+      total += arr[i];
+    } else if (typeof arr[i] === 'string') {
+      total += arr[i].length;
+    } else if (typeof arr[i] === 'boolean') {
+      total += arr[i] ? 1 : 0;
+    }
+  }
+
+  return total;
+}
 
 
 // Iteration #4: Calculate the average
 // Level 1: Array of numbers
 const numbersAvg = [2, 6, 9, 10, 7, 4, 1, 9];
 
-function averageNumbers() {}
+function averageNumbers(numbers) {
+  let total = 0;
+
+  for (let i = 0; i < numbers.length; i++) {
+    total += numbers[i];
+  }
+
+  return total / numbers.length;
+}
 
 
 // Level 2: Array of strings
 const wordsArr = ['seat', 'correspond', 'linen', 'motif', 'hole', 'smell', 'smart', 'chaos', 'fuel', 'palace'];
 
-function averageWordLength() { }
+function averageWordLength(words) {
+  let totalLength = 0;
+
+  for (let i = 0; i < words.length; i++) {
+    totalLength += words[i].length;
+  }
+
+  return totalLength / words.length;
+}
+
 
 // Bonus - Iteration #4.1
-function avg() {}
+function avg(arr) {
+  let total = 0;
+
+  for (let i = 0; i < arr.length; i++) {
+    if (typeof arr[i] === 'number') {
+      total += arr[i];
+    } else if (typeof arr[i] === 'string') {
+      total += arr[i].length;
+    } else if (typeof arr[i] === 'boolean') {
+      total += arr[i] ? 1 : 0;
+    }
+  }
+
+  return total / arr.length;
+}
+
 
 // Iteration #5: Unique arrays
 const wordsUnique = [
@@ -52,15 +120,33 @@ const wordsUnique = [
   'bring'
 ];
 
-function uniquifyArray() {}
+function uniquifyArray(words) {
+  if (!words) return null;
+
+  let unique = [];
 
+  for (let i = 0; i < words.length; i++) {
+    if (unique.indexOf(words[i]) === -1) {
+      unique.push(words[i]);
+    }
+  }
+
+  return unique;
+}
 
 
 // Iteration #6: Find elements
 const wordsFind = ['machine', 'subset', 'trouble', 'starting', 'matter', 'eating', 'truth', 'disobedience'];
 
-function doesWordExist() {}
+function doesWordExist(words, word) {
+  for (let i = 0; i < words.length; i++) {
+    if (words[i] === word) {
+      return true;
+    }
+  }
 
+  return false;
+}
 
 
 // Iteration #7: Count repetition
@@ -78,41 +164,68 @@ const wordsCount = [
   'matter'
 ];
 
-function howManyTimes() {}
+function howManyTimes(words, word) {
+  let count = 0;
 
+  for (let i = 0; i < words.length; i++) {
+    if (words[i] === word) {
+      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(matrix) {
+  let maxProduct = 0;
+
+  for (let i = 0; i < matrix.length; i++) {
+    for (let j = 0; j < matrix[i].length; j++) {
 
+      if (j + 3 < matrix[i].length) {
+        let product = matrix[i][j] * matrix[i][j+1] * matrix[i][j+2] * matrix[i][j+3];
+        if (product > maxProduct) maxProduct = product;
+      }
+
+      if (i + 3 < matrix.length) {
+        let product = matrix[i][j] * matrix[i+1][j] * matrix[i+2][j] * matrix[i+3][j];
+        if (product > maxProduct) maxProduct = product;
+      }
+
+    }
+  }
+
+  return maxProduct;
+}
 
 
 
 // The following is required to make unit tests work.
-/* Environment setup. Do not modify the below code. */
 if (typeof module !== 'undefined') {
   module.exports = {
     maxOfTwoNumbers,
@@ -127,4 +240,4 @@ if (typeof module !== 'undefined') {
     howManyTimes,
     greatestProduct
   };
-}
+}
\ No newline at end of file