i wouldn´t ask her directly: Would you give me your phone number?
i wouldn´t also aks her directly anyway. I would say: "hey, this was very nice to talk to you, but, my friends up there are waiting for me and i can´t keep them waiting any longer." ´Cause if you made everything right (neg´s, push&pull...etc) then she would ask YOU for your number. Also i wouldn´t give her my mobile to type the number in...or let´s say, it depends to your intent, if you just want to get her number, then use a pen with a peace of paper, if you really want to call her again you can give your mobile to her that she types her number in. i think if she doesn´t ask for your number after you sad that :have to go...bla bla bla friends waiting blablabla

then you haven´t done everything right.
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sry if my english is not the best^^
i´m from germany and i´m still a student.Anyway, i hope you understand my posts, if not contact me and i´ll try to say it in other words^^
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