Re: Get number or get Facebook?
If I were you, I would exchange facebooks. This will obviously help you figure out if she is, in fact, a real woman and it will give you a step toward her giving you her number. Or, to take the pressure off of her and sort of disqualify her, try to get her number by saying something like "You're so cool, if nothing more, we should definitely hangout as friends. What's your number?" Tricking her into giving you her number as "friends" makes her think it's harmless to do so because you wouldn't be just another guy she may have to get rid of later if she doesn't like you. Then, once you get her out with you, you can easily flip that. A woman will always feel comfortable if there are no expectations. Hope this helps and good luck!
When we are no longer able to change the situation, we are challenged to change ourselves.