diff --git a/calculator.js b/calculator.js
index caf34db..543c406 100644
--- a/calculator.js
+++ b/calculator.js
@@ -7,9 +7,20 @@ function add(num1, num2){
   return num1 + num2;
 }
 
-function substract(num1, num2){
+function subtract(num1, num2){
   return num1 - num2;
 }
 
+function multiply(num1, num2){
+	return num1*num2;
+}
+
+function divide(num1, num2){
+	return num1/num2;
+}
+
 module.exports.add = add;
+module.exports.subtract = subtract;
+module.exports.multiply = multiply;
+module.exports.divide = divide;
 module.exports.isNumber = isNumber;
diff --git a/index.html b/index.html
index cc6a9d9..fe3100e 100644
--- a/index.html
+++ b/index.html
@@ -21,7 +21,9 @@ <h1>Silly Calculator</h1>
     <input type="text" name="" id="num1" value="1" />
     <select id="operator" size="1">
       <option value="add">+</option>
-      <option value="substract">-</option>
+      <option value="subtract">-</option>
+	  <option value="multiply">*</option>
+      <option value="divide">/</option>
     </select>
     <input type="text" id="num2" value="1" />
     <div>=</div>
diff --git a/main.js b/main.js
index 957a234..30bc2f1 100644
--- a/main.js
+++ b/main.js
@@ -13,8 +13,14 @@ window.onload = function(){
     if (operator == "add"){
       document.getElementById('ans').value = add(num1, num2);
     }
-    else if (operator == "substract"){
-      document.getElementById('ans').value = substract(num1, num2);
+    else if (operator == "subtract"){
+      document.getElementById('ans').value = subtract(num1, num2);
+    }
+	else if (operator == "multiply"){
+      document.getElementById('ans').value = multiply(num1, num2);
+    }
+	else if (operator == "divide"){
+      document.getElementById('ans').value = divide(num1, num2);
     }
     else {
       alert("Bad operator!")
diff --git a/test/test_calculator.js b/test/test_calculator.js
index 13f6205..f69ad14 100644
--- a/test/test_calculator.js
+++ b/test/test_calculator.js
@@ -4,7 +4,22 @@ var cal = require('../calculator.js')
 describe('Calculator', function(){
   describe('add', function(){
     it('add', function(){
-      assert.equal('2', cal.add(1, 1));
+      assert.equal('5.73', cal.add(4.5, 1.23));
+    })
+  })
+  describe('subtract', function(){
+    it('subtract', function(){
+      assert.equal('0', cal.subtract(1, 1));
+    })
+  })
+  describe('multiply', function(){
+    it('multiply', function(){
+      assert.equal('3.75', cal.multiply(3, 1.25));
+    })
+  })
+  describe('divide', function(){
+    it('divide', function(){
+      assert.equal('3', cal.divide(24, 8));
     })
   })
 })