Getting a girl's number over facebook?

[Corsica]

Hey everyone,

So I met this girl in my social circle, we had a great conversation, then got split up in the course of our activity. I think she kind of auto rejected on me as the next time I saw her she was kind of cold and we didn't talk. The next time I saw her I talked to her again and she seemed to warm back up, however this annoying guy kept interrupting and I was not able to move her or get her number. Then today, I knew she was going to be at this group event, but I was only going to be able to be there briefly, so I planned on talking to her a bit and getting her number. Well she got there after me and I was not able to talk to her before I had to go.
I'm not sure when I'll see her again if I even do.

So my question is: what is a good way I could get her number? I don't want to look like I'm chasing or being weird, so I thought just a casual message over Facebook or something? What do you guys think?

And for future reference, how do you usually go about getting a girl one on one in group settings where all the guys seem to want to crowd you and get some of the girl's attention as well?
Thanks for any thoughts guys! I'm just starting out so I have a lot to learn.

 

[Novacane]

Build a little rapport online and ask for her number with a reason. Ex. "Hey _______ why don't we go out for dinner/movie/lunch sometime this week?" If she agrees ask for contact details and your set to go. As for dealing with other guys that try to get her attention don't play into the game let them hover and coo and haw at her aha, just be chilled about it when you have the chance talk to her for a while and YOU exit the conversation first, it'll get her thinking as to why you out of all these guys aren't trying to win her attention, building attraction. Hope I've helped.

 

[mkivtt]

Yea I wouldn't do it over Facebook, except using the method in the post above: message her a bit, see if she responds, make her laugh, go back and forth a few times and if she likes it, go "hey, send me your number so I can text you instead... easier than using Facebook " or something. But if you still see her, just ask in person.