Custom Column Duration.Days (include first day)

Hello

I am trying to create a custom column to show the difference in days between 2 dates. 

I need to include the first date in the count

Ex

pcreatedon: 12/5/2023

createdon: 12/6/2023 

I need this to show as 2 instead of the 1 day difference we usually use.

I am using:

Duration.Days([pcreatedon]-[createdon])

How do I get the count to show 2??