I am trying to create an Excel workbook where I have all entire months invoices and each invoice is on a new sheet in the workbook. How can I make it so that the invoice number on each sheet will be incremented by 1. So that the first invoice on the first sheet might be 2011-001, and the next invoice on the next sheet could automatically be 2011-002. Is this possible? All the information about sequential numbers that I could find said that this requires writing macros, which I am not able to do (I don't believe) in the MS Excel for Mac 2008 version. Any ideas how to do this would be greatly appreciated!