by Advanced filter
For Excel 2003, go Data-Filter-Advanced Filters
List range is your 2nd column, Criteria range is 1st column
Check unique records only will show 1 result of each account

by formula
At new column, type =IF(ISERROR(VLOOKUP(B10,$A:$A,1,FALSE)),"Not
Exist","Exist")
Drag down the formula.

Hope it helps.
eksh

"kix" wrote:

I have two columns 1st column has certain account numbers, the 2nd has those
same numbers plus a couple hundred more. I want to eliminate the account
numbers in 2nd column that do not exist in 1st column. I don't know how to
write a
formula for this.

Thank you.