Can I create a field that calculates number of days from a date field?

Hi all,

I need a field that will calculate the number of days elapsed whatever date is entered into the date field, and update that number of days based on the calendar/computer calendar date.  Does that make sense?

https://www.dropbox.com/s/arkmnsxjkl4r156/AFBS_FacilitySpecialCareList 02.pdf

I set up the form so that my boss can add or subtract clients from the list.  Each client needs to have its own "Days since added to the list" number. Sorta like a little aging report.

Is this possible?

Many thanks,

Laura