Added test cases

02_calculator/calculator.js

@@ -0,0 +1,32 @@
+function add () {
+	
+}
+
+function subtract () {
+	
+}
+
+function sum () {
+	
+}
+
+function multiply () {
+	
+}
+
+function power() {
+	
+}
+
+function factorial() {
+	
+}
+
+module.exports = {
+	add,
+	subtract,
+	sum,
+	multiply,
+    power,
+	factorial
+}