restrict entry in one cell if there is anything in the cell next t

[Carol Sitea]

I need to restrict entry in one cell if there is anything in the cell next to
it. Only one entry per line. How can I do this?

Thanks in advance,
Carol

A B
Fed Other
1 1
2 1
3 1
4 1
5 3
6 2

 

[Alan]

You need Validation on the Data toolbar.
Data > Validation, in the 'Allow' box, select 'Custom' In the 'Formula' box
that appears, enter =B1=0
Use the Error Alert tab to enter a suitable error message,
Regards,
Alan.

 

[Alan]

I should have said, do this in cell A1,
Alan.

You need Validation on the Data toolbar.
Data > Validation, in the 'Allow' box, select 'Custom' In the 'Formula'
box that appears, enter =B1=0
Use the Error Alert tab to enter a suitable error message,
Regards,
Alan.