diff --git a/.DS_Store b/.DS_Store
new file mode 100644
index 000000000..783ebf08d
Binary files /dev/null and b/.DS_Store differ
diff --git a/src/recursion.js b/src/recursion.js
index 12ca0a3d7..543dcf995 100644
--- a/src/recursion.js
+++ b/src/recursion.js
@@ -1,60 +1,160 @@
 // Solve all of the following prompts using recursion.
-
+ 
 // 1. Calculate the factorial of a number.  The factorial of a non-negative integer n,
 // denoted by n!, is the product of all positive integers less than or equal to n.
 // Example:  5! = 5 x 4 x 3 x 2 x 1 = 120
 // factorial(5);  // 120
-var factorial = function(n) {
-};
-
+var factorial = function(n, total, i = n) {
+    if(total === undefined){total = 1}
+    if(i < 0){
+        return null;
+    }else if(i === 0){
+        return total
+    }
+    total *= i;
+    i--;
+    return factorial(n, total, i)
+};
+ 
 // 2. Compute the sum of an array of integers.
 // Example:  sum([1, 2, 3, 4, 5, 6]);  // 21
-var sum = function(array) {
+var sum = function(array, total = 0, i = 0) {
+    if (i === array.length){return total}
+    total += array[i];
+    i++;
+    return sum(array,total,i)
 };
-
+ 
 // 3. Sum all numbers in an array containing nested arrays.
 // Example: arraySum([1,[2,3],[[4]],5]); // 15
 var arraySum = function(array) {
 };
-
+ 
 // 4. Check if a number is even.
 var isEven = function(n) {
+    if(n === 0){
+        return true;
+    }else if(n === 1){
+        return false;
+    }
+    if(n < 0){
+        n = n + 2;
+    }else if(n > 0){
+    n = n - 2;
+}
+    return isEven(n);
 };
-
+ 
 // 5. Sum all integers below a given integer.
 // sumBelow(10); // 45
 // sumBelow(7); // 21
-var sumBelow = function(n) {
-};
-
+var sumBelow = function(n,total = 0,i = n) {
+    if(i === 0 ){
+        return total;
+    }
+    if(n > 0){
+        i--;
+        total = total + i;
+    }else if(n < 0){
+        i++;
+        total = total + i;
+    }
+   
+ 
+    return sumBelow(n,total,i);
+};
+ 
 // 6. Get the integers in range (x, y).
 // Example:  range(2, 9);  // [3, 4, 5, 6, 7, 8]
-var range = function(x, y) {
-};
-
+var range = function(x, y, array = [], i = x) {
+    if (x === y || x === y + 1) {
+        return array;
+    }
+    if (x > y) {
+        i--;
+    } else if (x < y) {
+        i++;
+    }
+    if (i === y) {
+        return array;
+    }
+    array.push(i);
+   
+   
+    return range(x, y, array, i);
+};
+ 
 // 7. Compute the exponent of a number.
 // The exponent of a number says how many times the base number is used as a factor.
 // 8^2 = 8 x 8 = 64.  Here, 8 is the base and 2 is the exponent.
 // Example:  exponent(4,3);  // 64
 // https://www.khanacademy.org/computing/computer-science/algorithms/recursive-algorithms/a/computing-powers-of-a-number
-var exponent = function(base, exp) {
-};
-
+var exponent = function(base, exp, i = exp, total = 1) {
+    if (exp === 0) {
+        return 1;
+    } else if (exp === 1) {
+        return base;
+    }
+    if (i === 0){
+        return total;
+    }
+    if (exp < 0) {
+        total /= base;
+        i++;
+    } else if (exp > 0) {
+        total *= base;
+        i--;
+        }
+   
+    return exponent(base,exp,i, total);
+};
+ 
 // 8. Determine if a number is a power of two.
 // powerOfTwo(1); // true
 // powerOfTwo(16); // true
 // powerOfTwo(10); // false
-var powerOfTwo = function(n) {
-};
-
+var powerOfTwo = function(n, total = n) {
+    if(n === 1){
+        return true
+    }else if(n === 0){
+        return false
+    }
+    if(total === 2){
+        return true
+    }else if(total < 2){
+        return false
+    }
+    total = total/2
+    return powerOfTwo(n, total)
+ 
+};
+ 
 // 9. Write a function that accepts a string a reverses it.
-var reverse = function(string) {
-};
-
+var reverse = function(string, i = string.length-1, finalString="") {
+    if(i < 0){
+        return finalString
+    }
+    finalString = finalString.concat(string.charAt(i))
+    i--
+    return reverse(string, i, finalString)
+};
+ 
 // 10. Write a function that determines if a string is a palindrome.
-var palindrome = function(string) {
-};
-
+var palindrome = function(string, i = string.length-1, back = "") {
+    string = string.replace(" ", "")
+    back = back.replace(" ", "")
+    if(i < 0){
+        if(back.toLowerCase() == string.toLowerCase()){
+            return true;
+        }else{
+            return false;
+        }
+    }
+    back = back.concat(string.charAt(i));
+    i--;
+    return palindrome(string, i, back);
+};
+ 
 // 11. Write a function that returns the remainder of x divided by y without using the
 // modulo (%) operator.
 // modulo(5,2) // 1
@@ -62,17 +162,28 @@ var palindrome = function(string) {
 // modulo(22,6) // 4
 var modulo = function(x, y) {
 };
-
+ 
 // 12. Write a function that multiplies two numbers without using the * operator  or
 // JavaScript's Math object.
-var multiply = function(x, y) {
-};
-
+var multiply = function(x, y, i = y, total = 0) {
+    if(i === 0){
+        return total
+    }
+    if( y < 0){
+        total -= x
+        i++
+    } else if(y > 0){
+        total += x
+        i--
+    }
+    return multiply(x, y, i, total)
+};
+ 
 // 13. Write a function that divides two numbers without using the / operator  or
 // JavaScript's Math object.
 var divide = function(x, y) {
 };
-
+ 
 // 14. Find the greatest common divisor (gcd) of two positive numbers.  The GCD of two
 // integers is the greatest integer that divides both x and y with no remainder.
 // Example:  gcd(4,36);  // 4
@@ -80,60 +191,124 @@ var divide = function(x, y) {
 // https://www.khanacademy.org/computing/computer-science/cryptography/modarithmetic/a/the-euclidean-algorithm
 var gcd = function(x, y) {
 };
-
+ 
 // 15. Write a function that compares each character of two strings and returns true if
 // both are identical.
 // compareStr('house', 'houses') // false
 // compareStr('', '') // true
 // compareStr('tomato', 'tomato') // true
-var compareStr = function(str1, str2) {
-};
-
+var compareStr = function(str1, str2, i = 0, truth = 0) {
+ 
+    if(i === str1.length && i === str2.length){
+ 
+        if(truth === str1.length && truth === str2.length){
+            return true
+        }else{
+            return false
+        }
+    }
+    if(str1.length === str2.length){
+        if(str1.charAt(i) === str2.charAt(i)){
+            truth++
+        }
+    }else{
+        return false
+    }
+    i++
+    return compareStr(str1, str2, i, truth)
+};
+ 
 // 16. Write a function that accepts a string and creates an array where each letter
 // occupies an index of the array.
-var createArray = function(str){
-};
-
+var createArray = function(str, i = 0, final = []){
+    // if (final[0] == str[0]) {
+    //     final.push(i);
+    //     i++;
+    // }
+    // if (str == final) {
+    //     return final;
+    // }
+ 
+    //String.prototype.split() cant use
+    if(i === str.length){
+        return final;  
+    }
+    final.push(str.charAt(i));
+    i++;
+    return createArray(str, i, final);
+};
+ 
 // 17. Reverse the order of an array
-var reverseArr = function (array) {
-};
-
+var reverseArr = function (array, i = array.length - 1, finalArr = []) {
+    if (i < 0) {
+        return finalArr;
+    }
+    finalArr.push(array[i]);
+    i--;
+    return reverseArr(array, i, finalArr);
+};
+ 
 // 18. Create a new array with a given value and length.
 // buildList(0,5) // [0,0,0,0,0]
 // buildList(7,3) // [7,7,7]
-var buildList = function(value, length) {
-};
-
+var buildList = function(value, length, i = length, array = []) {
+    if (i === 0) {
+        return array;
+    }
+        array.push(value);
+   
+    i--;
+    return buildList(value, length, i, array)
+};
+ 
 // 19. Count the occurence of a value inside a list.
 // countOccurrence([2,7,4,4,1,4], 4) // 3
 // countOccurrence([2,'banana',4,4,1,'banana'], 'banana') // 2
-var countOccurrence = function(array, value) {
-};
-
+var countOccurrence = function(array, value, i = 0, number = 0) {
+    /*
+make an if statement says if value is inside the array => number++
+*/
+    //Base Case =>  i equals array.length - 1
+    if(i === array.length){
+        return number
+    }
+    if(array[i] === value){
+        number++
+    }
+    i++
+    return countOccurrence(array, value, i, number)
+};
+ 
 // 20. Write a recursive version of map.
 // rMap([1,2,3], timesTwo); // [2,4,6]
-var rMap = function(array, callback) {
-};
-
+var rMap = function(array, callback, i = 0, arr = []) {
+    if (i === array.length) {
+        return arr;
+    }
+    arr.push(callback(array[i]));
+    i++
+    return rMap(array, callback, i, arr);
+};
+ 
 // 21. Write a function that counts the number of times a key occurs in an object.
 // var testobj = {'e': {'x':'y'}, 't':{'r': {'e':'r'}, 'p': {'y':'r'}},'y':'e'};
 // countKeysInObj(testobj, 'r') // 1
 // countKeysInObj(testobj, 'e') // 2
 var countKeysInObj = function(obj, key) {
 };
-
+ 
 // 22. Write a function that counts the number of times a value occurs in an object.
 // var testobj = {'e': {'x':'y'}, 't':{'r': {'e':'r'}, 'p': {'y':'r'}},'y':'e'};
 // countValuesInObj(testobj, 'r') // 2
 // countValuesInObj(testobj, 'e') // 1
 var countValuesInObj = function(obj, value) {
 };
-
+ 
 // 23. Find all keys in an object (and nested objects) by a provided name and rename
 // them to a provided new name while preserving the value stored at that key.
 var replaceKeysInObj = function(obj, key, newKey) {
 };
-
+ 
 // 24. Get the first n Fibonacci numbers.  In the Fibonacci Sequence, each subsequent
 // number is the sum of the previous two.
 // Example:  0, 1, 1, 2, 3, 5, 8, 13, 21, 34.....
@@ -141,26 +316,51 @@ var replaceKeysInObj = function(obj, key, newKey) {
 // Note:  The 0 is not counted.
 var fibonacci = function(n) {
 };
-
+ 
 // 25. Return the Fibonacci number located at index n of the Fibonacci sequence.
 // [0,1,1,2,3,5,8,13,21]
 // nthFibo(5); // 5
 // nthFibo(7); // 13
 // nthFibo(3); // 2
-var nthFibo = function(n) {
-};
-
+var nthFibo = function(n, i = 0, number = 0, array = [0, 1, 1]) {
+    if (n < 0) {
+        return null;
+    }
+    if (array.length-1 >= n) {
+        return array[n];
+    } else {
+        array.push((array[array.length - 1] + array[array.length - 2]));
+    }
+    return nthFibo(n, i, number, array);
+};
+ 
 // 26. Given an array of words, return a new array containing each word capitalized.
 // var words = ['i', 'am', 'learning', 'recursion'];
 // capitalizedWords(words); // ['I', 'AM', 'LEARNING', 'RECURSION']
-var capitalizeWords = function(input) {
-};
-
+var capitalizeWords = function(input, i = 0, array = []) {
+    if (input.length === array.length) {
+        return array;
+    }
+    array.push(input[i].toUpperCase());
+    i++
+    return capitalizeWords(input, i, array);
+};
+ 
 // 27. Given an array of strings, capitalize the first letter of each index.
 // capitalizeFirst(['car', 'poop', 'banana']); // ['Car', 'Poop', 'Banana']
-var capitalizeFirst = function(array) {
-};
-
+var capitalizeFirst = function(array, i = 0, arr = [], firstChar,string) {
+    if (array.length === arr.length) {
+        return arr;
+    }
+    string = array[i];
+    firstChar = string.slice(0,1);
+    firstChar = firstChar.toUpperCase();
+    string = string.replace(string.charAt(0), firstChar)
+    arr.push(string);
+    i++;
+    return capitalizeFirst(array, i, arr, string);
+};
+ 
 // 28. Return the sum of all even numbers in an object containing nested objects.
 // var obj1 = {
 //   a: 2,
@@ -172,75 +372,127 @@ var capitalizeFirst = function(array) {
 // nestedEvenSum(obj1); // 10
 var nestedEvenSum = function(obj) {
 };
-
+ 
 // 29. Flatten an array containing nested arrays.
 // Example: flatten([1,[2],[3,[[4]]],5]); // [1,2,3,4,5]
 var flatten = function(arrays) {
 };
-
+ 
 // 30. Given a string, return an object containing tallies of each letter.
 // letterTally('potato'); // {'p':1, 'o':2, 't':2, 'a':1}
-var letterTally = function(str, obj) {
-};
-
+var letterTally = function(str, obj = {}, i = 0) {
+    if (i === str.length){
+        return obj
+    }
+    if(isNaN(obj[str[i]])){
+    obj[str[i]] = 0
+    }
+    obj[str[i]] += 1
+    i++
+    return letterTally(str, obj, i)
+};
+ 
 // 31. Eliminate consecutive duplicates in a list.  If the list contains repeated
 // elements they should be replaced with a single copy of the element. The order of the
 // elements should not be changed.
 // Example: compress([1, 2, 2, 3, 4, 4, 5, 5, 5]) // [1, 2, 3, 4, 5]
 // Example: compress([1, 2, 2, 3, 4, 4, 2, 5, 5, 5, 4, 4]) // [1, 2, 3, 4, 2, 5, 4]
-var compress = function(list) {
-};
-
+var compress = function(list, arr = [], i = 0) {
+    if(i === list.length){
+        return arr
+    }
+ 
+    if(list[i] != arr[arr.length-1]){
+        arr.push(list[i]);
+    }
+    i++
+    return compress(list, arr, i)
+};
+ 
 // 32. Augment every element in a list with a new value where each element is an array
 // itself.
 // Example: augmentElements([[],[3],[7]], 5); // [[5],[3,5],[7,5]]
 var augmentElements = function(array, aug) {
 };
-
+ 
 // 33. Reduce a series of zeroes to a single 0.
 // minimizeZeroes([2,0,0,0,1,4]) // [2,0,1,4]
 // minimizeZeroes([2,0,0,0,1,0,0,4]) // [2,0,1,0,4]
-var minimizeZeroes = function(array) {
-};
-
+var minimizeZeroes = function(array, arr = [], i = 0) {
+    if(i === array.length){
+        return arr
+    }
+ 
+    if(array[i] != 0){
+        arr.push(array[i])
+    }else if(array[i] === 0 && arr[arr.length-1] != 0){
+        arr.push(array[i])
+    }
+ 
+    i++
+    return minimizeZeroes(array, arr, i)
+ 
+};
+ 
 // 34. Alternate the numbers in an array between positive and negative regardless of
 // their original sign.  The first number in the index always needs to be positive.
 // alternateSign([2,7,8,3,1,4]) // [2,-7,8,-3,1,-4]
 // alternateSign([-2,-7,8,3,-1,4]) // [2,-7,8,-3,1,-4]
-var alternateSign = function(array) {
-};
-
+var alternateSign = function(array, arr = [], i = 0) {
+    if(i === array.length){
+        return arr
+    }
+   
+ 
+   
+    if(i%2 != 0){
+        if(array[i] < 0){
+            arr.push(array[i] * 1)
+        }else if(array[i] > 0){
+            arr.push(array[i] * -1)
+        }
+    }else if(i%2 === 0){
+        if(array[i] < 0){
+            arr.push(array[i] * -1)
+        }else if(array[i] > 0){
+            arr.push(array[i] * 1)
+        }
+    }
+    i++
+    return alternateSign(array, arr, i)
+};
+ 
 // 35. Given a string, return a string with digits converted to their word equivalent.
 // Assume all numbers are single digits (less than 10).
 // numToText("I have 5 dogs and 6 ponies"); // "I have five dogs and six ponies"
 var numToText = function(str) {
 };
-
+ 
 // *** EXTRA CREDIT ***
-
+ 
 // 36. Return the number of times a tag occurs in the DOM.
 var tagCount = function(tag, node) {
 };
-
+ 
 // 37. Write a function for binary search.
 // Sample array:  [0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15]
 // console.log(binarySearch(5)) will return '5'
-
+ 
 var binarySearch = function(array, target, min, max) {
 };
-
+ 
 // 38. Write a merge sort function.
 // Sample array:  [34,7,23,32,5,62]
 // Sample output: [5,7,23,32,34,62]
 var mergeSort = function(array) {
 };
-
-
-
+ 
+ 
+ 
 //-----------------------------------
 // DON'T REMOVE THIS CODE -----------
 //-----------------------------------
-
+ 
 if ((typeof process !== 'undefined') &&
     (typeof process.versions.node !== 'undefined')) {
     module.exports = {
@@ -269,5 +521,5 @@ if ((typeof process !== 'undefined') &&
         alternateSign,
     };
 }
-
+ 
 //-----------------------------------
\ No newline at end of file