diff --git a/08_calculator/calculator.js b/08_calculator/calculator.js
index c22e8d2..996c821 100644
--- a/08_calculator/calculator.js
+++ b/08_calculator/calculator.js
@@ -1,25 +1,25 @@
-const add = function() {
-	
+const add = function(a, b) {
+	return a + b;
 };
 
-const subtract = function() {
-	
+const subtract = function(a, b) {
+	return a - b;
 };
 
-const sum = function() {
-	
+const sum = function(a, b) {
+	return a + b
 };
 
-const multiply = function() {
-
+const multiply = function(a, b) {
+  return a * b;
 };
 
-const power = function() {
-	
+const power = function(a, b) {
+	return Math.pow(a, b);
 };
 
-const factorial = function() {
-	
+const factorial = function(a, b) {
+	return a / b;
 };
 
 // Do not edit below this line