How to befriend a really shy guy?

Ok... so I've been crushing on this guy for a while, and we are practically friendly acquaintances. We talk here and there, but we're still not friends yet. Homecoming's in 2 more days I know it's too early and I can't quite rush it. The problem is, he's pretty introverted and doesn't have many people to talk to. He's a nice guy, but he never smiles when I pass by him. He tends to avoid eye contact. Does that mean he hates everyone, he's shy, or he's a grumpy person? Most importantly... can I SMILE at him when I see him before classes? I mean, I am shy too and I don't want my smile to get rejected if he doesn't smile back. Also, how can I get his number without seeming like I like him?
How to befriend a really shy guy?
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