Alphanumeric Code Generator

Hello everyone. Who can help me on how to generate a code for a SupplierID consist of alphanumneric character same as this format A001. The first Letter of the Code is taken from the suppliers name and then added according e.g if supplier name is Microsoft the code looks like this M001 and if i add other supplier with the name of Maxil the code shode be M002. I have done the first part i.e picking us the first letter from the supplier's name to add to the code but how can i generate the numeric number automaticly while checking the max value please help. Im using vb6 for this application and msaccess for my database. Thanks a lot.