Is it possible to do two criteria for cells entered in a column using
data validation. I already prevent numeric entries by using a custom
validation criteria eg =NOT(ISNUMBER(A5)) but I would also like to
prevent or alert to duplicates in the column using another custom
criteria eg =COUNTIF($A$1:$A$100,A5)<=1. Can these two be combined in
any way to achieve the desired result? I value any assistance.

Kind Regards
Graham Haughs
Turriff
Scotland