If a girl gives you her number after planning on studying with her does she want you to ask her out?

i had talked to her a bit in the past cles so i asked if she wanted to study and we planned to do it then she asked to exchange numbers incase something goes wrong. did she want me to ask her out? i did not and when talking to her while studying she said she had a boy friend. which i dont want to doubt. but their is no hard evidence that she does. but she shows a lot of interest in me and is touchy towards me so i cant think of any reason why she would say that unless it is true. but she said she likes to go out and party a lot. like on every friday get drunk. if she had a bf would she be doing that? what would her reason be to say she has a boyfriend if she shows so much interest in me? i am american and she is asian tibet. could that be a reason? could she be uncomfortable telling her parents she is interested in me or something?