perform calculations on Document records DFFs

Summary:

Is there a way to perform calculations or derivable segments in document records DFFs based on the other segments. the calculations could be the difference between the dates, computing total values, etc.

Can we achieve it via table type or any other type of value sets or default values or any another way like sandbox?

Content (required):

We have a document record type named "Planned Annual Leave". This is submitted by an employee just for reporting purposes as per the business process at the customer side. Thus we opened fields for From_Date, To_date, Total_days having their own value sets. Now it is required by the customer that total_days should be automatically calculated as per the from_date and to_date entered.