diff --git a/app/helper_functions.py b/app/helper_functions.py
index d12f42f..04db1ce 100644
--- a/app/helper_functions.py
+++ b/app/helper_functions.py
@@ -34,7 +34,7 @@ def is_number(value: str) -> bool:
         # Convert the string to a float
         num = float(value)
         # Check if the number is positive
-        if num <= 0:
+        if num < 0:
             return False
         # Check if the string contains "+" or "-"
         if "+" in value or "-" in value: