Highlighting duplicate values in a column

Our department is involved in project managing office moves. The
moving department is given an excel 2002 spreadsheet and they fill out
the names of the people moving (column A) along with their extension
number (column B). I would like it to pop up a message if an
extension number is entered and is a duplicate of one already entered,
giving the person's name it's duplicated with.

Any help would be gratefully received

TIA

As a rough and ready solution I would use Col C and have the equation in C6 for example (assuming data runs from row 2)...

=If(countif(B$1:B5,B6)>0,"Duplicate","")

Rather than pop up a message, how about if you set the conditional
formatting for the cells in column B to highlight if a duplicate
extension is entered?

Set conditional formatting to "formula is" and use this formula
(altered, of course, to fit your data):
=COUNTIF($B$2:$B$17,B2)>1

Then set it to highlight in red or yellow to indicate a duplicate.

[email protected] (Jeff) wrote in message news:<[email protected]>...
> Our department is involved in project managing office moves. The
> moving department is given an excel 2002 spreadsheet and they fill out
> the names of the people moving (column A) along with their extension
> number (column B). I would like it to pop up a message if an
> extension number is entered and is a duplicate of one already entered,
> giving the person's name it's duplicated with.
>
> Any help would be gratefully received
>
> TIA

Ignore this, I've managed to use the validate function