diff --git a/maths/decimal_isolate.py b/maths/decimal_isolate.py
index 1b8f6cbca..cdf43ea5d 100644
--- a/maths/decimal_isolate.py
+++ b/maths/decimal_isolate.py
@@ -4,7 +4,7 @@ https://stackoverflow.com/questions/3886402/how-to-get-numbers-after-decimal-poi
 """
 
 
-def decimal_isolate(number, digit_amount):
+def decimal_isolate(number: float, digit_amount: int) -> float:
 
     """
     Isolates the decimal part of a number.