There's probably a better way but this seems to work. On Sheet1: conditional
format formula
=SUMPRODUCT(--(A1='Sheet2'!A1:A3000),'Sheet2'!A1:A3000)<A1

Don't tell my wife that I answered myself.


"David K." wrote in message
...
Hi,

How can I highlight cells in a list of numbers on Sheet1 where the number
of occurrences of that number on Sheet2 is not equal to 1?

Sheet1 has a list of unique numbers that will not change.
Sheet2 is an entry sheet were a list will be entered.
Assuming both lists will start in A1 and continue in column A.

On Sheet1 how can I highlight cells in the list where the number of
occurrences of that number on Sheet2 is not equal to 1?

In other words, using the list on Sheet1, I want to know if a number has
not been entered or entered more than once on Sheet2.

Hope this makes sense to someone. Thanks for any ideas.
--
David K.