diff --git a/index.js b/index.js
index 3bb4d07..ce28494 100644
--- a/index.js
+++ b/index.js
@@ -4,7 +4,31 @@
  * Depending on the operation, either add up all of the numbers or subtract all of the numbers, from left to right.
  * @returns {number} The result of either adding all numbers or subtracting all numbers, depending on the arguments added to the command line.
  */
-function calculator() {}
+
+ // const arrNum = number.map(Number);
+ 
+ function calculator() {
+    const operator = process.argv[2];
+    const number = process.argv[3];
+    let result = Number(number);
+    if (operator === undefined) {
+        return "No operation provided...";
+    } else if (number === undefined) {
+        return "No numbers provided...";
+    }
+    for (let i = 4; i < process.argv.length; i++) {
+        if (operator === 'plus') {
+            result += Number(process.argv[i]);
+        } else if (operator === 'minus') {
+            result -= Number(process.argv[i]);
+        } else {
+            return `Invalid operation: ${operator}`;
+        }
+    }
+    return result;
+}
+ 
+calculator()
 
 // Don't change anything below this line.
 module.exports = calculator;
diff --git a/package-lock.json b/package-lock.json
index 99b1c39..ce6f0ea 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -5,6 +5,7 @@
   "requires": true,
   "packages": {
     "": {
+      "name": "8-0-javascript-on-your-machine-lab",
       "version": "1.0.0",
       "license": "ISC",
       "devDependencies": {