Use data validation type custom with a formula of

=COUNTIF(A:A,A1)=1

--
__________________________________
HTH

Bob

"BABYPINK" wrote in message
...
Hi

I need to enter unique numbers (Manually) into a column

I just want to make sure there are no duplicates, the format is

SA123456
SA365489
SA222222

Hopefully if I do enter a duplicate the column will not let me

Thanks