I'm with WC2 on this one. Forget about the random bs questions or finding a reason to approach her. She knows whats going on and the transition from the question to her number is weird.
At this point I'm pretty quick and direct. There are so many girls out there that I don't waste time if they aren't interested. I just ask her what her name is, then I tell her that I think she's pretty and that I want to take her on a date. Almost in those exact words. If she gives me her number, great. If not, that's great too, because now I don't have to waste my time, effort, etc on her and can focus on girls that are interested.
Anyway, to answer your question approaching "even the hottest model girl" the trick is to develop your confidence and self-image (inner game, I guess) to the point that you can approach her and truly feel like you are qualifying her (which comes from developing yourself and knowing you have options). If you approach a girl in complete confidence and stay in control of the situation, meaning that you are the leader, the one that she is looking to, then you set the tone and she'll respond. When you approach like that, it doesn't matter what you say. You'll communicate your attractiveness to her on a deeper level than what words do. Seriously, it's all inner game.