Numeric Passkey
 

When I try to use m bluetooth with another device, it ask for my numeric passkey. What is this and how do I know what to enter?

Try 0000 (4 zeros).

its almost always 0000 as juwaack said, but if that doesnt work and its a device that can have a custom pin code, ask the owner (if its someone else) or check the documentation that came with it (if you have it)

that isnt working for me. It keeps telling me "unable to pair with my computer". I tried the last 4 digits of my cell number too.

normally the numeric passkey is a key you create that the other phone has to type in jus to make sure that it's a secure connection and not just anybody ... b/c right after you type it in the other person has to type in the same passkey you typed in.. if they don't type in the right passkey then the connection will not be made...

Could be 1234 also, my GPS puck uses 1234 instead of 0000

You might also try "1111" its not the default by worked on mine when "0000" didn't.
You may also need to specify the bluetooth connect pw from the pc side similar to when you pair the bb's themselves.