diff --git a/index.js b/index.js
index 3bb4d07..ea38a80 100644
--- a/index.js
+++ b/index.js
@@ -3,8 +3,32 @@
  * The first argument passed after the filename should be either "plus" or "minus", which represents the kind of calculation that will be done. Every argument afterwards should be a number.
  * 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
+    const command = process.argv[2]
+    const numbers = process.argv
+    if (numbers.length <= 2){
+        return "No operation provided..."
+    } else if (numbers.length <= 3){
+        return "No numbers provided..."
+    } else if (command === "plus"){
+        for (let i = 3; i < numbers.length; i++){
+            result += Number(numbers[i])
+        }
+    } else if (command === "minus"){
+        if (numbers.length > 3){
+            result = Number(numbers[3])
+            for (let x = 4; x < numbers.length; x++){
+                result -= Number(numbers[x])
+            }
+        }
+    }  else if (command !== "plus" || "minus"){
+        return `Invalid operation: ${command}`
+    }
+    return result
+}
+calculator()
 
 // Don't change anything below this line.
-module.exports = calculator;
+module.exports = calculator;
\ No newline at end of file