How should I go about getting a girls number?

First of all, it's stalker. Second of all, she'd only think that if you were to like, knock on her front door and ask her, if you just get to know her better and then ask her some other time, then there's nothing wrong with that. Sometimes girls are just intimidated the first time and need a chance to warm up to the idea.

It actually might be annoying and uncomfortable to her, stalker doesnt always mean itself literally... sometimes, or, now in days, its kind of like being annoying, or bothering.