Suppose your account numbers are in column A. In a helper column you
can put this formula in row 2 (assuming you have a header row):

=COUNTIF(A$2:A2,A2)

and copy this down your 10,000 rows. This will count how many times
the account number on a particular row has occurred up to that point.
If you apply a custom filter on this column for Is Greater Than 1,
then you will see all the duplicated account numbers.

Hope this helps.

Pete

On May 15, 6:59*pm, chadhable
wrote:
I have a list of customer account numbers. *The list contains about
10,000 numbers. *I have imported our list into Excel. *I know that by
sorting and looking at each number I will find the duplicate numbers,
but I was wondering if there is another way to find duplicate numbers.
If there is a way to highlight the number or stopping at that point, but
any information would be helpful.

Thank you for your time and your help.

--
chadhable