"Dianne W" wrote:
How do I create a formula using the date item
was put into inventory and the date you open
to spreadsheet (every time) and figure the
number of days in inventory?

If A1 contains the date that the item was put into inventory, the following
formula computes the number of days between then and the current date:

=TODAY() - A1

TODAY() is not exactly "the date you open the spreadsheet" -- imagine if you
open the workbook just before midnight, and you evaluate that formula just
after midnight.

But I suspect it will do what you want.