I have two columns of numbers. One is a large list with say 11,000 random
serial numbers. The other is a smaller list of 600 serial numbers. I want to
find if any serial numbers are listed in both of the columns. I want to
identify which number appear in both columns and highlight them. Or have a
way of identifying this in prehaps a third column.

Hi!

Using conditional formatting to highlight duplicates:

Assume the range is A1:A11000 and B1:B600.

Select the range A1:A11000
Goto FormatConditional Format
Formula is: =OR(A1=B$1:B$600)
Click the Format button
Select a cell fill color
OK out

Select the range B1:B600
Repeat the process but use
Formula is: =OR(B1=A$1:A$11000)

Biff

-----Original Message-----
I have two columns of numbers. One is a large list with
say 11,000 random
serial numbers. The other is a smaller list of 600 serial
numbers. I want to
find if any serial numbers are listed in both of the
columns. I want to
identify which number appear in both columns and
highlight them. Or have a
way of identifying this in prehaps a third column.
.