Why?
When you need that value in a report, query or form, simply calculate it.
Storing it in the table would be redundant if the data used to calculate it
is also there. What if a user changes one of the values? How will the
calculated value be updated?
There are exceptions. If you want to store a calculation at a point in time
(rates change, prices go up, etc.) then there are ways to do so. Post back
with what you aare doing for more details. Are you storing the calculation
in the same table upon which your form is based? Are you requiring
variables from the user that may change? Etc.
Rick B