Assume your range is A1:A100...

<Format<Conditional Formatting...
From the drop down box choose "Formula Is"
Enter this formula: =COUNTIF($A$1:$A$100,A1)1
Choose a format (e.g. background color, text color) to display for duplicates
Select "OK"
Copy the formatting of this cell down to the end of your range

Note: Change the reference of A1:A100 to fit your data.
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Regards,
Dave


"Baylee" wrote:

I have to keep track of load ticket numbers for our trucking company. I have
it set up so they are all in one column. Is there a way I can set it up to
warn about duplicate entries? Version I use is MS Office 2002. Any help would
be much appreciated!
Thanks. Linda