You have almost answered your own question "validation"
see entries in topics index for data validation
you want to include a check on the length if text,
or on the range if a number
http://www.contextures.com/tiptech.html
and it would probably also be shown in one of the videos at
http://www.datapigtechnologies.com/ExcelMain.htm

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HTH,
David McRitchie, Microsoft MVP - Excel [site changed Nov. 2001]
My Excel Pages: http://www.mvps.org/dmcritchie/excel/excel.htm
Search Page: http://www.mvps.org/dmcritchie/excel/search.htm

"Bonbon" wrote in message ...
Hi again, following up my last post with product codes such as 0001, 0002.
Does anyone know what i should eneter for the formula to validate these cells
so only a 4 digit code could be entered and lets say the limit is 4444. what
is the formula?

Thx in advance
Bonbon