diff --git a/08_calculator/calculator.js b/08_calculator/calculator.js
index c22e8d2..7d5163b 100644
--- a/08_calculator/calculator.js
+++ b/08_calculator/calculator.js
@@ -1,25 +1,42 @@
-const add = function() {
-	
+const add = function(numOne, numTwo) {
+	return numOne + numTwo
 };
 
-const subtract = function() {
-	
+const subtract = function(numOne, numTwo) {
+  return numOne - numTwo
 };
 
-const sum = function() {
-	
+const sum = function (arraySum) {
+  resultSum = 0
+  arraySum.forEach(number => resultSum += number);
+  return resultSum
 };
 
-const multiply = function() {
-
+const multiply = function(...args) {
+  resultMul = 1
+  arrayMul = [...args]
+  arrayMul.forEach(number => resultMul *= number)
+  return resultMul
 };
 
-const power = function() {
-	
+const power = function (num, pow) {
+  powSum = 1
+  for (i = 0; i < pow; i++) {
+    powSum *= num
+  }
+  return powSum
 };
 
-const factorial = function() {
-	
+const factorial = function(factorial) {
+  factorialSum = 1; 
+
+  if (factorial === 0) {
+    return 1;
+  }
+  for (i = factorial; i > 0; i--) {
+    factorialSum *= i
+  }
+  return factorialSum
 };
 
 // Do not edit below this line
diff --git a/08_calculator/calculator.spec.js b/08_calculator/calculator.spec.js
index 3507452..44010a2 100644
--- a/08_calculator/calculator.spec.js
+++ b/08_calculator/calculator.spec.js
@@ -5,73 +5,73 @@ describe('add', () => {
 		expect(calculator.add(0,0)).toBe(0);
 	});
 
-	test.skip('adds 2 and 2', () => {
+	test('adds 2 and 2', () => {
 		expect(calculator.add(2,2)).toBe(4);
 	});
 
-	test.skip('adds positive numbers', () => {
+	test('adds positive numbers', () => {
 		expect(calculator.add(2,6)).toBe(8);
 	});
 });
 
 describe('subtract', () => {
-	test.skip('subtracts numbers', () => {
+	test('subtracts numbers', () => {
 		expect(calculator.subtract(10,4)).toBe(6);
 	});
 });
 
 describe('sum', () => {
-	test.skip('computes the sum of an empty array', () => {
+	test('computes the sum of an empty array', () => {
 		expect(calculator.sum([])).toBe(0);
 	});
 
-	test.skip('computes the sum of an array of one number', () => {
+	test('computes the sum of an array of one number', () => {
 		expect(calculator.sum([7])).toBe(7);
 	});
 
-	test.skip('computes the sum of an array of two numbers', () => {
+	test('computes the sum of an array of two numbers', () => {
 		expect(calculator.sum([7,11])).toBe(18);
 	});
 
-	test.skip('computes the sum of an array of many numbers', () => {
+	test('computes the sum of an array of many numbers', () => {
 		expect(calculator.sum([1,3,5,7,9])).toBe(25);
 	});
 });
 
 describe('multiply', () => {
-	test.skip('multiplies two numbers', () => {
+	test('multiplies two numbers', () => {
 		expect(calculator.multiply(2,4)).toBe(8);
 	});
 
-	test.skip('multiplies several numbers', () => {
+	test('multiplies several numbers', () => {
 		expect(calculator.multiply(2,4,6,8,10,12,14)).toBe(645120);
 	});
 });
 
 describe('power', () => {
-	test.skip('raises one number to the power of another number', () => {
+	test('raises one number to the power of another number', () => {
 		expect(calculator.power(4,3)).toBe(64); // 4 to third power is 64
 	});
 });
 
 describe('factorial', () => {
-	test.skip('computes the factorial of 0', () => {
+	test('computes the factorial of 0', () => {
 		expect(calculator.factorial(0)).toBe(1); // 0! = 1
 	});
 
-	test.skip('computes the factorial of 1', () => {
+	test('computes the factorial of 1', () => {
 		expect(calculator.factorial(1)).toBe(1);
 	});
 
-	test.skip('computes the factorial of 2', () => {
+	test('computes the factorial of 2', () => {
 		expect(calculator.factorial(2)).toBe(2);
 	});
 
-	test.skip('computes the factorial of 5', () => {
+	test('computes the factorial of 5', () => {
 		expect(calculator.factorial(5)).toBe(120);
 	});
 
-	test.skip('computes the factorial of 10', () => {
+	test('computes the factorial of 10', () => {
 		expect(calculator.factorial(10)).toBe(3628800);
 	});
 });