I was able to determine the number of dates between two date fields. However, I am trying to formulate a total rent amount that would be based on a fixed monthly rate and adding any pro rated amount (or daily rate) for the odd number of days that follow (if any).
 
Example: monthly rate = $100.  Daily rate = $3.30 (100 / 30.33) 
Check-in date: 1/1/23
Check-out date: 3/10/23
Total = $233  ($100 Jan. +$100 Feb.) + 3.30 X 10 days Mar.  
The math does not work out correctly If simply provide a daily rate and multiply by total number of days.