Ok so I was at this party the other night and was talking to my friend while I noticed that a girl, who I hadn't seen in a while, noticed my attendance. She came up to me with a (male) friend and I greeted them nicely (first the guy, then her). Guy bounced after like a few min and we were having a three-way conv. We were just talking but her body was directed towards me ~90% of the chat and she was touching me whenever she spoke to me (like touching my shoulder pulling herself towards me). Eventually my friend felt the vibe as well and he bounced.

Started a bit of kino because she was comfortable with touching me. Then she told she might have to go back to her (male) friends soon because one of them was having his bday (in like 10min). The party was a sausage fest unfortunately. Because she had already shown me some pics (so she had her phone in hand) I told her to give me her number so that we could meet up later. Also told her to go back to her friends and that we would be in touch later. She was openly positive with the idea and then we split up. Didn't feel like k-closing her on that party (way too much coverage, plus dating other chicks in the same social circle) so didn't talk to her later.

Now comes the fun, her pn doesn't work. Normally you would say "ha, you got fucked" but she offered to add my # and let it ring, instead I gave her my phone and told her to put her details in (it's a power trick which I've gotten used to, should have rang the # though). I could add her on FB but I feel like that's kind of awkward. Could also ask a friend for her number but that also feels awkward because he observed the deal and was kind of jelly about it (this is the kind of hb a lot of guys want to be with).

So, options:
(1) Add on FB
(2) Ask my friend for her number

I would go for door No. 1 and wouldn't be making any reference to her giving you the wrong number... How to do that? Send her a message via facebook about some completely unrelated topic... a party coming up or an event of some sorts... gauge her reaction... could be that she was just careless or a bit tipsy when she wrote her number down... you have nothing to lose anyway, if she's not interested she'll just ignore your message or give you a lame answer... good luck!