diff --git a/index.js b/index.js
index 3bb4d07..4ed82da 100644
--- a/index.js
+++ b/index.js
@@ -4,7 +4,26 @@
  * 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() {
+    let result = 0
+    if(process.argv[2] == "plus" & process.argv.length > 3){
+        for(let x = 3; x < process.argv.length; x++){
+            result += parseInt(process.argv[x]);
+        }
+        return result;
+    }else if(process.argv[2] == "minus" & process.argv.length > 3){
+        result = parseInt(process.argv[3])
+        for(let x = 4; x < process.argv.length; x++){
+            result -= parseInt(process.argv[x]);
+        }
+        return result;
+    }else if(process.argv.length == 2){
+        return `No operation provided...`;
+    }else if(process.argv.length < 4){
+        return `No numbers provided...`;
+    }else{
+        return `Invalid operation: ${process.argv[2]}`;
+    }
+}
 // Don't change anything below this line.
 module.exports = calculator;