1998 bmw 316i coupe stereo code

I had some work done on my 1998 BMW 316i coupe so I need to enter the code for the radio to get it working again. Luckily enough I have the code for the radio, its 2158, however the numbers on the radio only go from 1 - 6. Do I need to use the + or - when entering the number?

M I'm pretty sure you only use 4 buttons. You use one for each digit and keep hitting the button to count up to the number your looking for.

Great thanks a million for replying Hammer Time. Its working again great
Glad to hear it. Thanks for posting back.