Add calculator solution

08_calculator/calculator.js

@@ -1,25 +1,52 @@
-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() {
-	
+
+let arrayDemo = [1, 2, 3, 4, 5];
+let sumNumbers = 0;
+for (i = 0; i < arrayDemo.length; i++){
+  sumNumbers += arrayDemo[i];
+}
+
+// const sum = function(array) {
+//   let sumNr = 0;
+//   for(i =0; i < array.length; i++){
+//     sumNr+= array[i];
+//   }
+//   return sumNr;
+// };
+
+const sum = function(array) {
+    return array.reduce((total, value) => total + value , 0);
 };
 
-const multiply = function() {
 
+const multiply = function(array) {
+  return array.reduce((value1, value2) => value1 * value2);
 };
 
-const power = function() {
-	
+const power = function(num1, num2) {
+	return Math.pow(num1,num2);
 };
 
-const factorial = function() {
-	
+let arrayN = [1, 2, 3, 4, 5];
+let sumN = 0;
+for (i = 0; i < arrayN.length; i++){
+  sumN += arrayN[i];
+}
+
+
+const factorial = function(num) {
+  let total = 1;
+  for(i=1; i <= num; i++) {
+    total *= i;
+  }
+  return total;
 };
 
 // Do not edit below this line