diff --git a/src/services/array-functions.js b/src/services/array-functions.js
index ff781d2..89857cd 100644
--- a/src/services/array-functions.js
+++ b/src/services/array-functions.js
@@ -5,7 +5,12 @@
 //add the returned value from fnc to the new array
 //return the new array
 export function map(theArray, fnc){
-
+    var myArray = [];
+    var theArrayLength = theArray.length;
+    for (var i = 0; i < theArrayLength; i++) {
+        myArray[i]=fnc(theArray[i]);
+    }
+    return myArray;
 }
 
 //create a new array
@@ -14,7 +19,14 @@ 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 myArray = [];
+    var theArrayLength = theArray.length;
+    for (var i = 0; i < theArrayLength; i++) {
+        if (fnc(theArray[i])){
+            myArray.push(theArray[i]);
+        }
+    }
+    return myArray;
 }
 
 
@@ -23,18 +35,26 @@ export function filter(theArray, fnc){
 //fnc will return true or false, if true return the item 
 //return null
 export function find(theArray, fnc){
-
+    var theArrayLength = theArray.length;
+    for (var i = 0; i < theArrayLength; i++) {
+        if (fnc(theArray[i])){
+            return theArray[i];
+        }
+    }
+    return null;
 }
 
 
 //return the last item in theArray
 export function findLast(theArray){
+    var length = theArray.length;
+    return theArray[length-1];
 
 }
 
 //return the first element of the array
 export function head(theArray){
-
+    return theArray[0];
 }
 
 //create a new array
@@ -42,7 +62,12 @@ export function head(theArray){
 //add the item from each loop to the new array
 //return the new array
 export function reverse(theArray){
-
+    var myArray = [];
+    var theArrayLength = theArray.length;
+    for (var i = theArrayLength-1; i >= 0; i--) {
+        myArray.push(theArray[i]);
+    }
+    return myArray;
 }
 
 //create a new array
@@ -50,6 +75,12 @@ 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){
+    var myArray = [];
+    var theArrayLength = theArray.length;
+    for (var i = 1; i < theArrayLength; i++) {
+        myArray.push(theArray[i]);
+    }
+    return myArray;
 
 }
 
@@ -64,5 +95,24 @@ 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){
-
+    function swap(a, b){
+        var temp = theArray[a];
+        theArray[a] = theArray[b];
+        theArray[b] = temp;
+    }
+    var flag;
+    var theArrayLength = theArray.length;
+    while(true){
+        flag = false;
+        for (var i = 0; i < theArrayLength; i++) {
+            if (theArray[i] > theArray[i+1]){
+                swap(i, i+1);
+                flag = true;
+            }
+        }
+        if (!flag){
+            break;
+        }
+    }
+    return theArray;
 }
\ No newline at end of file
diff --git a/src/tests/array-functions.test.js b/src/tests/array-functions.test.js
index 57ec72f..a77678c 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 {map,filter,find,findLast,head,sort,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];
 
@@ -18,7 +18,7 @@ describe("head", () => {
   });
 });
 
-
+//map should call the function for each array element and add that functioned element to the array
 describe("map", () => {
   it("should prepend Hello to each name", () => {
     expect(map(names,addHello)).toEqual([
@@ -34,24 +34,72 @@ describe("map", () => {
   });
 });
 
+//sort should order the list of numbers ascending
 describe("sort", () => {
   it("should return an array with numbers in order", () => {
     expect(sort(myNumbers)).toEqual([
-      1,2,3,4,5,7,22,55,99,1913
+      1,2,3,4,4,5,7,22,55,99,1913
     ]);
   });
 });
 
 //filter should return an array with names of length 3
 //["Jon","Bob","Ted","Axe"]
+describe("filter", () => {
+  it("should return names in array with length of 3", () => {
+    expect(filter(names,findThree)).toEqual([
+      "Jon",
+      "Bob",
+      "Ted",
+      "Axe"
+    ]);
+  });
+});
 
 //find should find one name of "Barney"
+describe("find", () => {
+  it("should call find Barney function and return the name 'Barney'", () => {
+    expect(find(names, findBarney)).toEqual("Barney");
+  });
+});
 
 //findLast should find the last name of "Axe"
+describe("findLast", () => {
+  it("should return the last element of an array '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"]
+describe("reverse", () => {
+  it("should return the elements in the array in opposite 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 elements of the array except the first", () => {
+    expect(tail(names)).toEqual([
+      "Bob",
+      "Ted",
+      "Barney",
+      "Lilly",
+      "Robin",
+      "Saul",
+      "Axe"
+    ]);
+  });
+});
 
diff --git a/src/tests/calculations.test.js b/src/tests/calculations.test.js
index 409e055..4702a17 100644
--- a/src/tests/calculations.test.js
+++ b/src/tests/calculations.test.js
@@ -1,7 +1,25 @@
-import {add, subtract, multiply,divide} from "../services/calculations";
+import {add, subtract, multiple,divide} from "../services/calculations";
 
 describe("add", () => {
   it("should add 1 and 2 and return 3", () => {
     expect(add(1, 2)).toBe(3);
   });
 });
+
+describe("subtract", () => {
+  it("should subtract 2 from 3 and return 1", () => {
+    expect(subtract(3, 2)).toBe(1);
+  });
+});
+
+describe("multiple", () => {
+  it("should multiply 2 and 3 and return 6", () => {
+    expect(multiple(2, 3)).toBe(6);
+  });
+});
+
+describe("divide", () => {
+  it("should divide 3 from 6 and return 2", () => {
+    expect(divide(6, 3)).toBe(2);
+  });
+});