How to get this guys number?

I'm starting to like this guy I'm in class with. We work together and today we just sat together and talked for like 20mins till class ended. We beak each other (beak= bug/tease) but he does with the two other girls in our group. The thing is he asked for my cell # one day in class but I was beaking him and didn't give it to him. That was 2 weeks ago and now school is almost ending and I want his number but don't know how to ask since I bugged him last time. Should I just go straight out and be like hey what's you're number?