diff --git a/src/__tests__/booleans.test.js b/src/__tests__/booleans.test.js
index 734201d5..d6477555 100644
--- a/src/__tests__/booleans.test.js
+++ b/src/__tests__/booleans.test.js
@@ -17,14 +17,14 @@ const {
 } = require('../booleans');
 
 describe('negate', () => {
-  xit('returns the opposite of the passed boolean value', () => {
+  it('returns the opposite of the passed boolean value', () => {
     expect(negate(true)).toBe(false);
     expect(negate(false)).toBe(true);
   });
 });
 
 describe('both', () => {
-  xit('returns true if both of the given booleans are true', () => {
+  it('returns true if both of the given booleans are true', () => {
     expect(both(true, true)).toBe(true);
     expect(both(true, false)).toBe(false);
     expect(both(false, true)).toBe(false);
@@ -33,7 +33,7 @@ describe('both', () => {
 });
 
 describe('either', () => {
-  xit('returns true if at least one of the given booleans are true', () => {
+  it('returns true if at least one of the given booleans are true', () => {
     expect(either(true, true)).toBe(true);
     expect(either(true, false)).toBe(true);
     expect(either(false, true)).toBe(true);
@@ -42,7 +42,7 @@ describe('either', () => {
 });
 
 describe('none', () => {
-  xit('returns true if neither of the given booleans are true', () => {
+  it('returns true if neither of the given booleans are true', () => {
     expect(none(true, true)).toBe(false);
     expect(none(true, false)).toBe(false);
     expect(none(false, true)).toBe(false);
@@ -51,7 +51,7 @@ describe('none', () => {
 });
 
 describe('one', () => {
-  xit('returns true if exactly one of the given booleans are true', () => {
+  it('returns true if exactly one of the given booleans are true', () => {
     expect(one(true, true)).toBe(false);
     expect(one(true, false)).toBe(true);
     expect(one(false, true)).toBe(true);
@@ -60,7 +60,7 @@ describe('one', () => {
 });
 
 describe('truthiness', () => {
-  xit('returns the truthiness of the given value', () => {
+  it('returns the truthiness of the given value', () => {
     expect(truthiness('')).toBe(false);
     expect(truthiness('dbbd')).toBe(true);
     expect(truthiness(0)).toBe(false);
@@ -74,7 +74,7 @@ describe('truthiness', () => {
 });
 
 describe('isEqual', () => {
-  xit('returns whether the two values are equal', () => {
+  it('returns whether the two values are equal', () => {
     expect(isEqual(true, false)).toBe(false);
     expect(isEqual(true, true)).toBe(true);
     expect(isEqual('true', 'true')).toBe(true);
@@ -86,7 +86,7 @@ describe('isEqual', () => {
 });
 
 describe('isGreaterThan', () => {
-  xit('returns true if the first number is strictly greater than the second', () => {
+  it('returns true if the first number is strictly greater than the second', () => {
     expect(isGreaterThan(1, 2)).toBe(false);
     expect(isGreaterThan(3, 2)).toBe(true);
     expect(isGreaterThan(4, 4)).toBe(false);
@@ -98,7 +98,7 @@ describe('isGreaterThan', () => {
 });
 
 describe('isLessThanOrEqualTo', () => {
-  xit('returns true if the first number is less than or equal to the second', () => {
+  it('returns true if the first number is less than or equal to the second', () => {
     expect(isLessThanOrEqualTo(1, 2)).toBe(true);
     expect(isLessThanOrEqualTo(3, 2)).toBe(false);
     expect(isLessThanOrEqualTo(4, 4)).toBe(true);
@@ -108,7 +108,7 @@ describe('isLessThanOrEqualTo', () => {
 });
 
 describe('isOdd', () => {
-  xit('returns whether the number is odd', () => {
+  it('returns whether the number is odd', () => {
     expect(isOdd(5)).toBe(true);
     expect(isOdd(6)).toBe(false);
     expect(isOdd(7)).toBe(true);
@@ -117,7 +117,7 @@ describe('isOdd', () => {
 });
 
 describe('isEven', () => {
-  xit('returns whether the number is even', () => {
+  it('returns whether the number is even', () => {
     expect(isEven(5)).toBe(false);
     expect(isEven(6)).toBe(true);
     expect(isEven(7)).toBe(false);
@@ -126,7 +126,7 @@ describe('isEven', () => {
 });
 
 describe('isSquare', () => {
-  xit('returns true if the number is a square', () => {
+  it('returns true if the number is a square', () => {
     expect(isSquare(9)).toEqual(true);
     expect(isSquare(4)).toEqual(true);
     expect(isSquare(5)).toEqual(false);
@@ -136,7 +136,7 @@ describe('isSquare', () => {
 });
 
 describe('startsWith', () => {
-  xit('returns whether the given string starts with the given character', () => {
+  it('returns whether the given string starts with the given character', () => {
     expect(startsWith('a', 'aardvark')).toBe(true);
     expect(startsWith('c', 'aardvark')).toBe(false);
     expect(startsWith('b', 'baardvark')).toBe(true);
@@ -146,7 +146,7 @@ describe('startsWith', () => {
 });
 
 describe('containsVowels', () => {
-  xit('returns whether the given string contains vowels', () => {
+  it('returns whether the given string contains vowels', () => {
     expect(containsVowels('cat')).toBe(true);
     expect(containsVowels('DOG')).toBe(true);
     expect(containsVowels('why')).toBe(false);
@@ -154,7 +154,7 @@ describe('containsVowels', () => {
 });
 
 describe('isLowerCase', () => {
-  xit('it returns true if the given string is lowercase', () => {
+  it('it returns true if the given string is lowercase', () => {
     expect(isLowerCase('abc')).toBe(true);
     expect(isLowerCase('abc213')).toBe(true);
     expect(isLowerCase('Abc')).toBe(false);
diff --git a/src/__tests__/numbers.test.js b/src/__tests__/numbers.test.js
index 253de15f..d610b3b3 100644
--- a/src/__tests__/numbers.test.js
+++ b/src/__tests__/numbers.test.js
@@ -13,7 +13,7 @@ const {
 } = require('../numbers');
 
 describe('add', () => {
-  xit('adds the two numbers together', () => {
+  it('adds the two numbers together', () => {
     expect(add(2, 1)).toEqual(3);
     expect(add(15, 76)).toEqual(91);
     expect(add(12, 0)).toEqual(12);
@@ -22,7 +22,7 @@ describe('add', () => {
 });
 
 describe('subtract', () => {
-  xit('subtracts the second number from the first', () => {
+  it('subtracts the second number from the first', () => {
     expect(subtract(2, 1)).toEqual(1);
     expect(subtract(1, 2)).toEqual(-1);
     expect(subtract(-2, 1)).toEqual(-3);
@@ -32,7 +32,7 @@ describe('subtract', () => {
 });
 
 describe('multiply', () => {
-  xit('multiplies the two numbers together', () => {
+  it('multiplies the two numbers together', () => {
     expect(multiply(10, 3)).toEqual(30);
     expect(multiply(-11, 5)).toEqual(-55);
     expect(multiply(-4, -9)).toEqual(36);
@@ -40,7 +40,7 @@ describe('multiply', () => {
 });
 
 describe('divide', () => {
-  xit('divides the first number by the second number', () => {
+  it('divides the first number by the second number', () => {
     expect(divide(20, 5)).toEqual(4);
     expect(divide(5, 2)).toEqual(2.5);
     expect(divide(2, 5)).toEqual(0.4);
@@ -49,7 +49,7 @@ describe('divide', () => {
 });
 
 describe('power', () => {
-  xit('returns the first number to the power of the second', () => {
+  it('returns the first number to the power of the second', () => {
     expect(power(5, 2)).toEqual(25);
     expect(power(2, 3)).toEqual(8);
     expect(power(10, 5)).toEqual(100000);
@@ -57,7 +57,7 @@ describe('power', () => {
 });
 
 describe('round', () => {
-  xit('rounds the number to the nearest integer', () => {
+  it('rounds the number to the nearest integer', () => {
     expect(round(2.1)).toEqual(2);
     expect(round(9.7)).toEqual(10);
     expect(round(5.5)).toEqual(6);
@@ -65,7 +65,7 @@ describe('round', () => {
 });
 
 describe('roundUp', () => {
-  xit('rounds the number up to the nearest integer', () => {
+  it('rounds the number up to the nearest integer', () => {
     expect(roundUp(2.1)).toEqual(3);
     expect(roundUp(9.7)).toEqual(10);
     expect(roundUp(5.5)).toEqual(6);
@@ -73,7 +73,7 @@ describe('roundUp', () => {
 });
 
 describe('roundDown', () => {
-  xit('rounds the number down to the nearest integer', () => {
+  it('rounds the number down to the nearest integer', () => {
     expect(roundDown(2.1)).toEqual(2);
     expect(roundDown(9.7)).toEqual(9);
     expect(roundDown(5.5)).toEqual(5);
@@ -81,7 +81,7 @@ describe('roundDown', () => {
 });
 
 describe('absolute', () => {
-  xit('returns the absolute value of the number', () => {
+  it('returns the absolute value of the number', () => {
     expect(absolute(-1)).toEqual(1);
     expect(absolute(1)).toEqual(1);
     expect(absolute(0)).toEqual(0);
@@ -93,7 +93,7 @@ describe('quotient', () => {
   // the first by the second, without the remainder
   // 18 divided by 7 is 2 remainder 4 (or 2.571...)
   // so the quotient of 18 and 7 is 2
-  xit('returns the quotient from dividing the first number by the second number', () => {
+  it('returns the quotient from dividing the first number by the second number', () => {
     expect(quotient(10, 3)).toEqual(3);
     expect(quotient(18, 7)).toEqual(2);
     expect(quotient(77, 10)).toEqual(7);
@@ -102,7 +102,7 @@ describe('quotient', () => {
 });
 
 describe('remainder', () => {
-  xit('returns the remainder when dividing the first number by the second number', () => {
+  it('returns the remainder when dividing the first number by the second number', () => {
     expect(remainder(10, 3)).toEqual(1);
     expect(remainder(18, 7)).toEqual(4);
     expect(remainder(77, 10)).toEqual(7);
diff --git a/src/__tests__/strings.test.js b/src/__tests__/strings.test.js
index e2c3c887..b19fd739 100644
--- a/src/__tests__/strings.test.js
+++ b/src/__tests__/strings.test.js
@@ -8,21 +8,21 @@ const {
 } = require('../strings');
 
 describe('sayHello', () => {
-  xit('returns "Hello world!" when passed "world"', () => {
+  it('returns "Hello world!" when passed "world"', () => {
     expect(sayHello('world')).toEqual('Hello, world!');
   });
 
-  xit('returns "Hello MCR Codes!" when passed "MCR Codes"', () => {
+  it('returns "Hello MCR Codes!" when passed "MCR Codes"', () => {
     expect(sayHello('MCR Codes')).toEqual('Hello, MCR Codes!');
   });
 
-  xit('returns "Hello fsghjdfkhgf!" when passed "fsghjdfkhgf"', () => {
+  it('returns "Hello fsghjdfkhgf!" when passed "fsghjdfkhgf"', () => {
     expect(sayHello('fsghjdfkhgf')).toEqual('Hello, fsghjdfkhgf!');
   });
 });
 
 describe('uppercase', () => {
-  xit('returns the uppercased string', () => {
+  it('returns the uppercased string', () => {
     expect(uppercase('abc')).toEqual('ABC');
     expect(uppercase('def')).toEqual('DEF');
     expect(uppercase('ghi')).toEqual('GHI');
@@ -30,7 +30,7 @@ describe('uppercase', () => {
 });
 
 describe('lowercase', () => {
-  xit('returns the lowercased string', () => {
+  it('returns the lowercased string', () => {
     expect(lowercase('ABC')).toEqual('abc');
     expect(lowercase('DEF')).toEqual('def');
     expect(lowercase('GHI')).toEqual('ghi');
@@ -38,7 +38,7 @@ describe('lowercase', () => {
 });
 
 describe('countCharacters', () => {
-  xit('returns the number of characters in the string', () => {
+  it('returns the number of characters in the string', () => {
     expect(countCharacters('fsfsgsfdg')).toEqual(9);
     expect(countCharacters('fsfsg')).toEqual(5);
     expect(countCharacters('')).toEqual(0);
@@ -46,7 +46,7 @@ describe('countCharacters', () => {
 });
 
 describe('firstCharacter', () => {
-  xit('returns the first character of the string', () => {
+  it('returns the first character of the string', () => {
     expect(firstCharacter('ABC')).toEqual('A');
     expect(firstCharacter('DEF')).toEqual('D');
     expect(firstCharacter('GHI')).toEqual('G');
@@ -54,11 +54,11 @@ describe('firstCharacter', () => {
 });
 
 describe('firstCharacters', () => {
-  xit('returns the first 4 characters of the string', () => {
+  it('returns the first 4 characters of the string', () => {
     expect(firstCharacters('sd32fg45', 4)).toEqual('sd32');
   });
 
-  xit('returns the first 2 characters of the string', () => {
+  it('returns the first 2 characters of the string', () => {
     expect(firstCharacters('asd', 2)).toEqual('as');
   });
 });
diff --git a/src/arrays.js b/src/arrays.js
index 822c49b7..2405bf20 100644
--- a/src/arrays.js
+++ b/src/arrays.js
@@ -1,61 +1,75 @@
 const getNthElement = (index, array) => {
-  // your code here
+
+return array[index % array.length]
+
 };
 
+
 const arrayToCSVString = array => {
-  // your code here
+  return (array.join());
 };
 
 const csvStringToArray = string => {
-  // your code here
-};
+  return string.split(',');
+}
 
 const addToArray = (element, array) => {
-  // your code here
+const count= array.push(element);
+console.log(array);
 };
 
 const addToArray2 = (element, array) => {
-  // your code here
+return array.concat(element);
+
 };
 
 const removeNthElement = (index, array) => {
-  // your code here
+  array.splice(index, 1);
+  console.log(array);
 };
 
 const numbersToStrings = numbers => {
-  // your code here
+return numbers.map(String);
 };
 
 const uppercaseWordsInArray = strings => {
-  // your code here
+  return strings.map(function(x){return x.toUpperCase();})
 };
 
 const reverseWordsInArray = strings => {
-  // your code here
+return strings.map(string=> string.split("").reverse().join(""));
 };
 
+
 const onlyEven = numbers => {
-  // your code here
+ const onlyEven = numbers.filter(number => number % 2===0);
+return onlyEven;
 };
 
 const removeNthElement2 = (index, array) => {
-  // your code here
+const NthElement2 = [...array];
+  NthElement2.splice(index, 1);
+   return NthElement2;
 };
 
 const elementsStartingWithAVowel = strings => {
-  // your code here
+  
+  return strings.filter(strings=> /^[aeiou]/gi.test(strings));
 };
 
 const removeSpaces = string => {
-  // your code here
+  return string.split(" ").join("");
 };
 
 const sumNumbers = numbers => {
-  // your code here
-};
+return sum = numbers.reduce((acc, number) => (acc + number));
+
+  };
 
 const sortByLastLetter = strings => {
-  // your code here
+  return strings.sort((a,b)=> a.charCodeAt(a.length-1)- b.charCodeAt(b.length-1));
+
+
 };
 
 module.exports = {
diff --git a/src/booleans.js b/src/booleans.js
index 5ff6cb55..e0f3ba6f 100644
--- a/src/booleans.js
+++ b/src/booleans.js
@@ -1,61 +1,67 @@
 function negate(a) {
-  // your code here
+  return a= !a;
 };
 
 function both(a, b) {
-  // your code here
+  return a&&b;
 };
 
 function either(a, b) {
-  // your code here
+  return a||b;
 };
 
 function none(a, b) {
-  // your code here
+ return !a&&!b ;
 };
 
 function one(a, b) {
-  // your code here
+  return a===!b;
 };
 
 function truthiness(a) {
-  // your code here
+  return (!!a);
 };
 
 function isEqual(a, b) {
-  // your code here
+  return a===b;
 };
 
 function isGreaterThan(a, b) {
-  // your code here
+  return a>b;
 };
 
 function isLessThanOrEqualTo(a, b) {
-  // your code here
+  return a<=b;
 };
 
 function isOdd(a) {
-  // your code here
-};
+  return (a%2>0);
+}
 
 function isEven(a) {
-  // your code here
+  return (a%2===0);
 };
 
 function isSquare(a) {
-  // your code here
-};
+    if (a>=0) {
+      let sr = Math.sqrt(a);
+      return((sr*sr)==a);
+    }
+  return false;
+  }
 
 function startsWith(char, string) {
-  // your code here
+  return string.startsWith(char);
 };
 
 function containsVowels(string) {
-  // your code here
+  const regex = /[aeiou]/gi
+return regex.test(string);
 };
 
 function isLowerCase(string) {
-  // your code here
+ const regex= /([A-Z])/g
+ return !regex.test(string);
 };
 
 module.exports = {
diff --git a/src/numbers.js b/src/numbers.js
index d3eab646..e1e214ed 100644
--- a/src/numbers.js
+++ b/src/numbers.js
@@ -1,46 +1,46 @@
-function add (a, b) {
-  // your code here
-}
+const add = (a, b) => {
+  return a+b;
+};
 
-function subtract (a, b) {
-  // your code here
-}
+const subtract = (a, b) => {
+  return a-b;
+};
 
-function multiply (a, b) {
-  // your code here
-}
+const multiply = (a, b) => {
+  return a*b;
+};
 
-function divide (a, b) {
-  // your code here
-}
+const divide =(a, b) => {
+  return a/b;
+};
 
-function power (a, b) {
-  // your code here
-}
+const power =(a, b) =>{
+  return Math.pow (a, b);
+};
 
-function round (a) {
-  // your code here
-}
+const round = (a) =>{
+  return Math.round(a);
+};
 
-function roundUp (a) {
-  // your code here
-}
+const roundUp = (a) =>{
+  return Math.ceil(a);
+};
 
-function roundDown (a) {
-  // your code here
-}
+const roundDown =(a)=> {
+  return Math.floor(a);
+};
 
-function absolute (a) {
-  // your code here
-}
+const absolute =(a)=> {
+  return Math.abs(a);
+};
 
-function quotient (a, b) {
-  // your code here
-}
+const quotient =(a, b)=> {
+  return Math.trunc(a/b);
+};
 
-function remainder (a, b) {
-  // your code here
-}
+const remainder =(a, b)=> {
+  return a%b;
+};
 
 module.exports = {
   add,
diff --git a/src/strings.js b/src/strings.js
index ce02affa..3bc37b78 100644
--- a/src/strings.js
+++ b/src/strings.js
@@ -1,25 +1,25 @@
 function sayHello (string) {
-  // your code here
+  return 'Hello, ' + (string) + '!';
 };
 
 function uppercase (string) {
-  // your code here
+  return (string).toUpperCase();
 };
 
 function lowercase (string) {
-  // your code here
+  return (string).toLowerCase();
 };
 
 function countCharacters (string) {
-  // your code here
+  return (string).length;
 };
 
 function firstCharacter (string) {
-  // your code here
+  return (string).charAt(0);
 };
 
 function firstCharacters (string, n) {
-  // your code here
+  return (string).substr(0, n);
 };
 
 module.exports = {