This works pretty good in day game if you have trouble trying to number close.

Carry some recipes in your pocket with your number on them and carry a pen.
Before you decide to part ways say, "lets play a game real quick before i go"
Shes most likely going to say okay.Get out the pen and paper and act like your writing something on it, put your hands behind your back and act like your putting it in a random hand, then put it in your back pocket (make sure you have an extra in your front pocket), say "pick a hand, open the empty hand, say "awe to bad", put hands in pockets, shes gonna ask what it was, say "well i was going to give you my number, but you lost". More than likely they'll give you their number instead.