diff --git a/index.js b/index.js
index 3bb4d07..d0458f2 100644
--- a/index.js
+++ b/index.js
@@ -4,7 +4,38 @@
  * 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() {}
+function calculator() {
+    const args = process.argv;
+
+    //Error Handling
+    if (args.length < 3) {
+        return "No operation provided...";
+    } else if (!(args.includes("plus") || args.includes("minus"))) {
+        return `Invalid operation: ${args[2]}`;
+    } else if (args.length < 4 || typeof Number(args[4]) !== "number") {
+        return "No numbers provided...";
+    }
+
+    //plus operator
+    if (args[2].toLowerCase() === "plus") {
+        let sum = 0;
+        for (let i = 3; i < args.length; i++) {
+            sum += Number(args[i]);
+        }
+        return sum;
+
+        //minus operator
+    } else if (args[2].toLowerCase() === "minus") {
+        let diff = Number(args[3]);
+        for (let i = 4; i < args.length; i++) {
+            diff -= Number(args[i]);
+        }
+        return diff;
+    }
+}
+
+
+
 
 // Don't change anything below this line.
 module.exports = calculator;
diff --git a/package-lock.json b/package-lock.json
index 4d451a9..e0f6e26 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -2873,13 +2873,10 @@
       }
     },
     "node_modules/json5": {
-      "version": "2.2.0",
-      "resolved": "https://registry.npmjs.org/json5/-/json5-2.2.0.tgz",
-      "integrity": "sha512-f+8cldu7X/y7RAJurMEJmdoKXGB/X550w2Nr3tTbezL6RwEE/iMcm+tZnXeoZtKuOq6ft8+CqzEkrIgx1fPoQA==",
+      "version": "2.2.3",
+      "resolved": "https://registry.npmjs.org/json5/-/json5-2.2.3.tgz",
+      "integrity": "sha512-XmOWe7eyHYH14cLdVPoyg+GOH3rYX++KpzrylJwSW98t3Nk+U8XOl8FWKOgwtzdb8lXGf6zYwDUzeHMWfxasyg==",
       "dev": true,
-      "dependencies": {
-        "minimist": "^1.2.5"
-      },
       "bin": {
         "json5": "lib/cli.js"
       },
@@ -3022,9 +3019,9 @@
       }
     },
     "node_modules/minimatch": {
-      "version": "3.0.4",
-      "resolved": "https://registry.npmjs.org/minimatch/-/minimatch-3.0.4.tgz",
-      "integrity": "sha512-yJHVQEhyqPLUTgt9B83PXu6W3rx4MvvHvSUvToogpwoGDOUQ+yDrR0HRot+yOCdCO7u4hX3pWft6kWBBcqh0UA==",
+      "version": "3.1.2",
+      "resolved": "https://registry.npmjs.org/minimatch/-/minimatch-3.1.2.tgz",
+      "integrity": "sha512-J7p63hRiAjw1NDEww1W7i37+ByIrOWO5XQQAzZ3VOcL0PNybwpfmV/N05zFAzwQ9USyEcX6t3UO+K5aqBQOIHw==",
       "dev": true,
       "dependencies": {
         "brace-expansion": "^1.1.7"
@@ -3033,12 +3030,6 @@
         "node": "*"
       }
     },
-    "node_modules/minimist": {
-      "version": "1.2.6",
-      "resolved": "https://registry.npmjs.org/minimist/-/minimist-1.2.6.tgz",
-      "integrity": "sha512-Jsjnk4bw3YJqYzbdyBiNsPWHPfO++UGG749Cxs6peCu5Xg4nrena6OVxOYxrQTqww0Jmwt+Ref8rggumkTLz9Q==",
-      "dev": true
-    },
     "node_modules/ms": {
       "version": "2.1.2",
       "resolved": "https://registry.npmjs.org/ms/-/ms-2.1.2.tgz",
@@ -6180,13 +6171,10 @@
       "dev": true
     },
     "json5": {
-      "version": "2.2.0",
-      "resolved": "https://registry.npmjs.org/json5/-/json5-2.2.0.tgz",
-      "integrity": "sha512-f+8cldu7X/y7RAJurMEJmdoKXGB/X550w2Nr3tTbezL6RwEE/iMcm+tZnXeoZtKuOq6ft8+CqzEkrIgx1fPoQA==",
-      "dev": true,
-      "requires": {
-        "minimist": "^1.2.5"
-      }
+      "version": "2.2.3",
+      "resolved": "https://registry.npmjs.org/json5/-/json5-2.2.3.tgz",
+      "integrity": "sha512-XmOWe7eyHYH14cLdVPoyg+GOH3rYX++KpzrylJwSW98t3Nk+U8XOl8FWKOgwtzdb8lXGf6zYwDUzeHMWfxasyg==",
+      "dev": true
     },
     "kleur": {
       "version": "3.0.3",
@@ -6290,20 +6278,14 @@
       "dev": true
     },
     "minimatch": {
-      "version": "3.0.4",
-      "resolved": "https://registry.npmjs.org/minimatch/-/minimatch-3.0.4.tgz",
-      "integrity": "sha512-yJHVQEhyqPLUTgt9B83PXu6W3rx4MvvHvSUvToogpwoGDOUQ+yDrR0HRot+yOCdCO7u4hX3pWft6kWBBcqh0UA==",
+      "version": "3.1.2",
+      "resolved": "https://registry.npmjs.org/minimatch/-/minimatch-3.1.2.tgz",
+      "integrity": "sha512-J7p63hRiAjw1NDEww1W7i37+ByIrOWO5XQQAzZ3VOcL0PNybwpfmV/N05zFAzwQ9USyEcX6t3UO+K5aqBQOIHw==",
       "dev": true,
       "requires": {
         "brace-expansion": "^1.1.7"
       }
     },
-    "minimist": {
-      "version": "1.2.6",
-      "resolved": "https://registry.npmjs.org/minimist/-/minimist-1.2.6.tgz",
-      "integrity": "sha512-Jsjnk4bw3YJqYzbdyBiNsPWHPfO++UGG749Cxs6peCu5Xg4nrena6OVxOYxrQTqww0Jmwt+Ref8rggumkTLz9Q==",
-      "dev": true
-    },
     "ms": {
       "version": "2.1.2",
       "resolved": "https://registry.npmjs.org/ms/-/ms-2.1.2.tgz",