How to mark duplicate names as "1"

[Sean15]

Hello:

I have a list with duplicates and unique names. How can I mark each duplicate and unique name with "1"

For example:

John James 1
John James
Peter Floyd 1
Mike Sutton 1
Mike Sutton

My goal is get total head count that should not include duplicates.

Thanks for your help.

Sean

 

[Fluff]

If your data is in A1 downwards put this in B1 & fill down
=IF(COUNTIF(A$1:A1,A1)>1,"",1)

 

[Sean15]

Excellent, thank you very much.

Sean

 

[Fluff]

Glad to help & thanks for the feedback

 

[Rick Rothstein]

Here is another formula you can try...

=LEFT(1,COUNTIF(A$1:A1,A1)=1)