There's a girl that works at a pizza shop... help please!?

So today I'm walking around the mall and I kinda stop by a Sabaro's for a slice of pizza, I notice the girl serving me is the exact kind of girl I'm looking for, shes cute, nice, and has a great sense of humor.... Now here's the kicker she doesn't know me at all... and I would like to get to know her allot better, so my options is some how muster up the courage and ask for her number, but what if she says no.. it might be embarring for me... please ladies and gents help with a good way to ask for her number or tell me if this might be creepy for her I'd really appreciate it!