Is it better to give a girl ur number or ask for it?

i no it sounds like its better to ask for theres, but if you think about it, if you give urs to them, they wont feel any obligation or anything to call, if they want to call, theyll feel fine abut it becuae i was the one to give it to them, if they dont want to hang out with me/call than they just wont call.......but if i ask for theres, and i call them and they dont really wanan hang out with me, there would be a wall of fakeness, and she might feel obligated....i dont know if im making sense, but i just hate obligation and fakeness....