I want to be able to enter data (whole number) in only one row cell from a
range of cell. An error message would show if data is entered in an other
cell in that range.

I am desperate to get an answer.
Thanks

Serge,
the following *array* formula (needs to be entered with
Shift+Ctrl+Enter) will test if there are more than one numbers in
A1:A100
=IF(SUM(--ISNUMBER(A1:A10))1, "One too many", "")

To test if you have more than one non-blank cells in the range (incl.
text), use:
=IF(SUM((1-ISBLANK(A1:B20)))1, "One too many", "")

HTH
Kostis Vezerides

I have been working on your response for the past hour with no result.
Refrased question: In a selected range of cell (7 cells) in one row I want
to enter a number in only one of those cell which will correspond to
information in the column header. If data is entered in an other cell in the
same range this needs to create an error.
Thanks
Serge

"vezerid" wrote:

Serge,
the following *array* formula (needs to be entered with
Shift+Ctrl+Enter) will test if there are more than one numbers in
A1:A100
=IF(SUM(--ISNUMBER(A1:A10))1, "One too many", "")

To test if you have more than one non-blank cells in the range (incl.
text), use:
=IF(SUM((1-ISBLANK(A1:B20)))1, "One too many", "")

HTH
Kostis Vezerides