there's a cute girl I work with, but idk how to get her number. I seem to be stuck in a situation where I need to talk to her to get her number, and I need her number to talk to her.

background: I'm pretty sure she likes me. I see her staring at me all the time (not being creepy, in a playful kinda way). we sorta talk at work, but it's hard, because she's a cashier, and I'm a cook. neither of us can ever get off at the same time because of how the schedule works. we're friends on facebook, but she rarely gets on. we've exchanged maybe 4 messages on there.

today, as I was leaving work, she asked if I was working tomorrow, because she was. I said yes, and she smiled and said "I'll see you tomorrow then"

my question is, I plan on sending her a message after work tomorrow on facebook to try and get her phone number. once I get that, I'll be fine. my problem is, idk what to say xD haha. I was planning on either "hey, can I have your number so I can ask you out sometime? " or perhaps "hey, can I have your number so we can talk outside of work? (perhaps a here too)"
the first one seems more direct, and the second seems more casual. which do you think I should use, or should I try something else?

Can't you just ask her out on facebook then get her number after she responds? Maybe ask if she wants to "tag along" (cliche but I like it) to whatever weekend shenanigans you have planned and give her your number. If you give your number, the implication is she should give hers. If she doesn't, you can ask for it. Or you can just ask her out directly on facebook.

creepers use facebook, ask her during a break at work

I work at a fast food restaurant. there's no such thing as a break

so I sent her
"hey, wanna swap phone numbers so I can ask you out sometime? "
and she gave me her number
...now what? should I call her or text her? a positive response to that means she's interested, right?

ASK HER OUT

call her