Just use the decimal or whole number options with a very small negative
number and the biggest negative number you will allow.

Or custom with =A1<0

--
HTH

Bob

(there's no email, no snail mail, but somewhere should be gmail in my addy)

"Courtney" wrote in message
...
I'm building a model where end-users must input expenses and revenues. In
the expense section I'd like to ensure that numbers are entered as
negatives,
or if they are entered as positives build a formula in the data validation
section that would automatically convert them to negative numbers. Any
idea
on how to do this?

Any insight would be appreciated.

Thanks!