Yes, you can do this with Data Validation.

1. Select your cell.
2. Choose "Validation..." from the Data Menu
3. Select either "Whole Number" or "Decimal" depending on your needs
4. Then select "Less than"
5. Type 0 in the Maximum field.
6. You can then also customize the error message when an invalid number is
entered if you wish

HTH,
Elkar


"George" wrote:

> I would like to protect a cell so that the number that is entered must be a
> negative number. Is this possible?
> e.g if 654 is entered - the cell rejects this positive number.
> George