how to show if you add a number twice in a column

[David Franciosy]

Hi I am in need of some help I am useing excel to track movements of are company products each load have a ref number which tells us what it is where it is going and so on. What I need to find out is a way for telling me if that number has already been enterted
He is a sample of numbers
we use
ab1234
what I need to do is if that number is used again I need it to inform me of it either turn the cell a different colour any help would be great

[VBA Noob]

Hi,

You could try conditional formatting. See links for help

http://www.cpearson.com/excel/duplic...tingDuplicates

http://www.contextures.com/xlCondFormat01.html

VBA Noob