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I need some help with MS Excel.

I have data in column A (ID Numbers)
I have data in column B (ID Numbers)

Column A has 37,622 ID numbers.
Column B has 41,547 ID numbers.

Here's what I am trying to find out:
1. I need a list of ID numbers that are not in both columns.
2. If the ID number is not in both columns can the ID number display as red in the original columns A & B?

With that many rows, the formula (which works) takes FOREVER to calculate.
fill down. This is the items in column A.
For Column B
fill down.
Calculate. Get dinner!
You still want a formula for conditional formatting? Will make the workbook fairly useless!
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This topic answers questions related to Microsoft Excel spreadsheet (or workbook) stand-alone or Mircrosoft Office Excel including Excel 2003, Excel 2007, Office 2000, and Office XP. You can get Excel help on Excel formulas(or functions), Excell macros, charting in Excel, advanced features, and the general use of Excel. This does not provide a general Excel tutorial nor the basics of using a spreadsheet. It provides specific answers to using Microsoft Excel only. If you do not see your Excel question answered in this area then please ask an Excel question here


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Bob Umlas


I`m a Microsoft Excel MVP (Most Valuable Professional) and have been since the inception of the program in 1995. I can answer every kind of Excel question except: API, Importing/exporting to other programs (powerpoint, word,...) Also check out my in-person training link at


Worked with MS Excel since version 0.99 (on the Mac!). Was contributing editor to Excellence Magazine, having written >300 articles. John Walkenbach said of me "I finally met someone who knows as much about Excel as I do."

Excellence, The Expert, Microsoft

BA in math, Hofstra University, 1965

Awards and Honors
Led sessions for the Convergence 2004-2006 seminar on Excel tips & tricks

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