diff --git a/src/stringcalculator.py b/src/stringcalculator.py
index 9c4ba2329e6eca184f2612930ab2735b14925e77..a1463b3c7c433283b37efb5099204564f965fd7b 100644
--- a/src/stringcalculator.py
+++ b/src/stringcalculator.py
@@ -7,17 +7,23 @@ class StringCalculator(IStringCalculator):
         if not numbers:
             return 0
 
-        # Prüfe auf das ungültige Format "1,\n"
-        if ",\n" in numbers:
-            raise ValueError("Ungültiges Zahlenformat: ',\\n' ist nicht erlaubt")
+        if numbers.startswith("//"):
+            if "\n" not in numbers:
+                raise ValueError("Ungültiges Format: Nicht vollständig")
+            delimiter_end_index = numbers.index("\n")
+            delimiter = numbers[2:delimiter_end_index]
+            numbers = numbers[delimiter_end_index + 1:]
+            numbers = numbers.replace(delimiter, ",")
 
-        # Trenne Zahlen anhand von Komma oder Zeilenumbruch
-        tokens = re.split(r",|\n", numbers)
+        numbers = numbers.replace("\n", ",")
 
-        # Konvertiere zu Integern und finde negative Zahlen
-        numbers_list = list(map(int, tokens))
-        negative_numbers = [num for num in numbers_list if num < 0]
+        # Split the string by commas, convert each value to an integer, and sum them up
+        try:
+            numbers_list = list(map(int, numbers.split(",")))
+        except ValueError:
+            raise ValueError("Ungültiges Zahlenformat: Enthält nicht-numerische Werte")
 
+        negative_numbers = [num for num in numbers_list if num < 0]
         if negative_numbers:
             raise ValueError(f"Negative nicht erlaubt: {negative_numbers}")