formula to put the number 1 in a column only against a unique number

[karyn]

Hey Ninjas
I know there will be a quicker way than the way I am currently doing this manually so I thought I would throw you amazing excel gurus the question
what I need to do is put the number 1 in a column when the number in the other column is unique - see the example below
really appreciate your help

cheers

REF
AP-19810 1
AP-19810
AP-19982 1
AP-19982
AP-19982
AP-20004 1
AP-20004
AP-20377 1
AP-20377
AP-20442 1
AP-20442
AP-20442
AP-20450 1
AP-20450

 

[Smallman]

Hi Karyn

Welcome to the Chandoo Forum.

Give the following a try.

=IF(COUNTIF($A$2:A2,A2)=1,1,"")

Take care

Smallman