Nissan Micra 2003 - Radio Problem?

I have recently purchased the above and the radio needs a code put in. Before I take it back to the dealer, I have a Radiopass (creditcard size piece of paper) which shows a long number, then a typ/model number, a serial number and then a four digit safety number which I presumed would be the code for the radio, however, it is not - any clues how I can get the code without having to take the car back to the dealer?