Can I cause checking a box to add 1 to a calculated form field? I have a field that sums the numbers entered in several previous fields and need to be able to add "1" if a checkbox is selected as well.

Can I cause checking a box to add 1 to a calculated form field?  I have a field that sums the numbers entered in several previous fields and need to be able to add "1" if a checkbox is selected as well.