Pulling Excel data

[Skyke2000]

I have and extremely large Excel file that I enter invoices into almost daily. Could someone help me with either a Visual basic program or a formula that could either flag or pull any duplicate data that is entered into it? Any help at all would be very appreciated.
Thanks!

[smurfy]

Need a bit more info here before I can think of anything to help.

1) How are the "invoices" entered
- data from each invoice entered into one table on one worksheet (or even multiple sheets - e.g. one worksheet tab for each day/week/month or whatever).
- each invoice has it's own worksheet tab within the workbook.

2) What duplicated information do you want to weed out? Any value or just selected fields?

3) How many records do you want to compare against for duplicates? Just the daily entries to make sure you haven't entered one twice??

[Skyke2000]

All the information is on one sheet, I enter: Company, Invoice Number, Date Shipped, Our Reference Number, Amount, and Date approved.
I want to be able to tell if I enter a duplicate Invioce number or our Reference Number. So I need to compare what I've entered to the entire worksheet.
Hope that helps. Thank you.