diff --git a/src/services/array-functions.js b/src/services/array-functions.js
index ff781d2..cf7d019 100644
--- a/src/services/array-functions.js
+++ b/src/services/array-functions.js
@@ -5,7 +5,11 @@
 //add the returned value from fnc to the new array
 //return the new array
 export function map(theArray, fnc){
-
+  var result = [];
+  for (var i=0, j=theArray.length; i < j; i++) {
+    result.push(fnc(theArray[i]));
+  }
+  return result;
 }
 
 //create a new array
@@ -14,7 +18,13 @@ export function map(theArray, fnc){
 //fnc will return true or false, if true add the item to the new array else do not
 //return the new array
 export function filter(theArray, fnc){
-
+  var result = [];
+  for (var i=0, j=theArray.length; i < j; i++) {
+    if (fnc(theArray[i])) {
+      result.push(theArray[i]);
+    }
+  }
+  return result;
 }
 
 
@@ -23,18 +33,23 @@ export function filter(theArray, fnc){
 //fnc will return true or false, if true return the item 
 //return null
 export function find(theArray, fnc){
-
+  for (var i=0, j=theArray.length; i < j; i++) {
+    if (fnc(theArray[i])) {
+      return theArray[i];
+    }
+  }
+  return false;
 }
 
 
 //return the last item in theArray
 export function findLast(theArray){
-
+  return theArray[theArray.length - 1];
 }
 
 //return the first element of the array
 export function head(theArray){
-
+  return theArray[0];
 }
 
 //create a new array
@@ -42,7 +57,11 @@ export function head(theArray){
 //add the item from each loop to the new array
 //return the new array
 export function reverse(theArray){
-
+  var result = [];
+  for (var i = theArray.length - 1; i >= 0; i--) {
+    result.push(theArray[i]);
+  }
+  return result;
 }
 
 //create a new array
@@ -50,7 +69,7 @@ export function reverse(theArray){
 //add the item from each loop to the new array except the first item
 //return the new array
 export function tail(theArray){
-
+  return theArray.slice(1);
 }
 
 //implement the most basic sorting algorithm there is
@@ -64,5 +83,26 @@ export function tail(theArray){
 //after each for loop check the variable, if true, continue the while loop
 //if false return theArray
 export function sort(theArray){
-
+  var sorted = false;
+  
+  while (sorted === false) {
+    
+    var swapRequired = false;
+    
+    for (var i=0, j=theArray.length; i<j; i++) {
+      if (theArray[i] > theArray[i+1]) {
+        var num = theArray[i];
+        theArray.splice(i, 1);
+        theArray.splice(i+1, 0, num);
+        swapRequired = true;
+      }
+    }
+    
+    if (swapRequired === false) {
+      sorted = true;
+    }
+    
+  }
+  
+  return theArray;
 }
\ No newline at end of file
diff --git a/src/services/calculations.js b/src/services/calculations.js
index 754df7c..afcf333 100644
--- a/src/services/calculations.js
+++ b/src/services/calculations.js
@@ -4,7 +4,7 @@ export function add(num1, num2){
 export function subtract(num1, num2){
   return num1 - num2;
 }
-export function multiple(num1, num2){
+export function multiply(num1, num2){
   return num1 * num2;
 }
 export function divide(num1, num2){
diff --git a/src/tests/array-functions.test.js b/src/tests/array-functions.test.js
index 171fffe..868749d 100644
--- a/src/tests/array-functions.test.js
+++ b/src/tests/array-functions.test.js
@@ -1,4 +1,4 @@
-import {map,filter,find,findLast} from "../services/array-functions";
+import {head,map,filter,sort,find,findLast,reverse,tail} from "../services/array-functions";
 const names = ["Jon","Bob","Ted","Barney","Lilly","Robin","Saul","Axe"];
 const myNumbers = [4,3,55,22,99,1913,7,5,4,2,1];
 
@@ -11,6 +11,7 @@ function findThree(name){
 function findBarney(name){
   return name === "Barney";
 }
+
 //head should find the first element in the array "Jon"
 describe("head", () => {
   it("should return the first element of an array 'Jon'", () => {
@@ -18,7 +19,7 @@ describe("head", () => {
   });
 });
 
-
+// map should perform a function on each individual element in an array
 describe("map", () => {
   it("should prepend Hello to each name", () => {
     expect(map(names,addHello)).toEqual([
@@ -34,6 +35,19 @@ describe("map", () => {
   });
 });
 
+//filter should return an array with names of length 3
+//["Jon","Bob","Ted","Axe"]
+describe("filter", () => {
+  it("should return an array of only the names that are 3 letters long", () => {
+    expect(filter(names,findThree)).toEqual([
+      "Jon",
+      "Bob",
+      "Ted",
+      "Axe"
+    ]);
+  });
+});
+
 describe("sort", () => {
   it("should return an array with numbers in order", () => {
     expect(sort(myNumbers)).toEqual([
@@ -42,16 +56,32 @@ describe("sort", () => {
   });
 });
 
-//filter should return an array with names of length 3
-//["Jon","Bob","Ted","Axe"]
-
 //find should find one name of "Barney"
+describe("find", () => {
+  it("should find one person whose name matches Barney", () => {
+    expect(find(names,findBarney)).toEqual("Barney");
+  });
+});
 
 //findLast should find the last name of "Axe"
+describe("findLast", () => {
+  it("should find the last name in the list, which is Axe", () => {
+    expect(findLast(names)).toEqual("Axe");
+  });
+});
 
 //reverse should return an array with the elements in the opposite order
 //["Axe","Saul","Robin","Lilly","Barney","Ted","Bob","Jon"]
-//tail should return all elements in an array except the first one
-//[Bob","Ted","Barney","Lilly","Robin","Saul","Axe"];
-
+describe("reverse", () => {
+  it("should return the array in reverse order", () => {
+    expect(reverse(names)).toEqual(["Axe","Saul","Robin","Lilly","Barney","Ted","Bob","Jon"]);
+  });
+});
 
+//tail should return all elements in an array except the first one
+//["Bob","Ted","Barney","Lilly","Robin","Saul","Axe"];
+describe("tail", () => {
+  it ("should return all the elements in the array except the first one", () => {
+    expect(tail(names)).toEqual(["Bob","Ted","Barney","Lilly","Robin","Saul","Axe"]);
+  });
+});
\ No newline at end of file
diff --git a/src/tests/calculations.test.js b/src/tests/calculations.test.js
index 409e055..a5ac068 100644
--- a/src/tests/calculations.test.js
+++ b/src/tests/calculations.test.js
@@ -5,3 +5,21 @@ describe("add", () => {
     expect(add(1, 2)).toBe(3);
   });
 });
+
+describe("subtract", () => {
+  it("should subtract 4 from 5 and return 1", () => {
+    expect(subtract(5, 4)).toBe(1);
+  });
+});
+
+describe("multiply", () => {
+  it ("should multiply 4 times 5 and return 20", () => {
+    expect(multiply(4,5)).toBe(20);
+  });
+});
+
+describe("divide", () => {
+  it ("should divide 100 by 4 and return 25", () => {
+    expect(divide(100,4)).toBe(25);
+  });
+});
\ No newline at end of file