Conditional Formatting to highlight duplicates across 3 worksheeets

[jerryroller]

I tried following a previous post but the instructions did not work. I have a workbook with 3 worksheets. Worksheet #1 has a list of Document #'s to choose from when logging in a new document. At present, we are cutting and pasting the next Document # in sequence into 1 of the 3 worksheets to log a correspondence. would to be able to just type a number in a cell, in any of the 3 worksheets and have Excel highlight that cell if I have typed in a # that already exists in another worksheet. Is this possible? Step-by-step instructions please.

 

[sijpie]

Are you document number sequential?

Perhaps it is easier to have one cell in each of the sheets that tells you the next number to use (which is the max of the numbers in the three sheets plus 1)