As Duane says, a clearer question is always helpful. You can see your
database; we cannot.
Overflow means that you have calculated a number which is larger than Access
can represent. Often this happens when you have a mathematical expression
which isn't doing exactly what you intend it to do! Dividing a large number
by a very small one can cause this error, among other things.
If you're getting the error from a Query, please open the Query in SQL view
and post the SQL text here.