How to get a pretty girl's telephone number who I like.

If you are sincere with the person in terms of why you want the number then it is a causal. I suppose a quick pick up line that you want it will not get you much. So I would suggest to get the know the person first before asking for the number. For me personally I cannot see a person as sincere if they ask for my phone number right off the bat. Ways on asking would perhaps be something like I really enjoyed our talk today and wondered if we can exchange phone numbers so we can meet up later for some coffee. This usually helps, however a girl may not be so quick unless she was very comfortable during the conversation.

dude why you need her number? The reason bill gates made computer for you is to free yourself from this kind of situation...just use your right hand and keep flipping pages with your left...

lol this reminds of an old pick up line I heard years ago....."I lost my phone number can I have yours" so there ya go try that lollol....well to me so long as she's showing interest too I dont see the problem of you just asking her for it!...just my thoughts :)

it is not as easy to get a girl's mobile number that quickly but the best approach is to talk with her decently and indulge her in the conversation and while leaving ask her for cell number and give a natural delightful smile.