If you use datavalidationallowcustom and

=A1<0

then they can't type in a positive number, otherwise you would need
an event macro that executes when pressing enter

Replace A1 with the cell you want to validate

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Regards,


Peo Sjoblom

"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!