Formula to highlight cells

[cooge]

Hi
I have a spreadsheet where there a 2 columns, say a & b. In column A I enter a lot of 6 digit No's. In column B I also enter a lot of 6 digit No's. The No's in Column B should match up to column A. I wnated to know if there is an easy way to higlight any No's that do not appear in column A but not in B.
I have used the V lookup tool in the past but wondered if there is a simple formula that can do it. I have also tried conditional formating which works on a cell for cell basis but cant get it to work for more than one cell at a time.

[NBVC]

I tried to answer this already here: http://www.excelforum.com/showthread.php?t=610475

If it doesn't do what you desire, please elaborate on that thread...

[cooge]

NBVC
This works a treat Thanks for your help, much appreciated.