Help! Tuesday is my last chance to get a guy's number.

I have liked a guy since October. The problem is, I am a sophomore and he is a senior and goes to another school. We see each other at sporting events and know each other through various friends. I have been too nervous to get his number *a)*because I doubt that he likes me and b) I fear rejection. I just want to be able to talk to him, even as friends, after he leaves. One of the last times I will see him is on Tuesday. Any tips on getting his number?