How Can I Get Justin Bieber Number To Ask If He Can Come And Sing At My Sweet 15?

Ok, one: It's generally the Sweet 16 that's a big deal.
Two: Justin Bieber has a Facebook/Twitter/email/phone number that are all available to the public. Check out his FB page for all info except Twitter. His Twitter name is @justinbieber. He tweets a lot and does reply to his fans/followers.

That's just my two cents. :)