Wooooo easy sonny boy. Closing in under a minute??? Before you go for that master the art of attaining numbers first. Step by step. If you fail to prepare then prepare to fail. In this case practice is your preperation. Wait until you feel comfortable with attaining numbers without a time limit.
Which brings me to my next point. Comfort. Number closing doesnt really have much to do with attraction at all. Its mainly comfort building. Establish SOME comfort before you exchange numbers.
Why can i imagine you to be the kinda guy that asks for her number?? (not saying you do - but just in case -)
PUA: Heres my phone, put your numbers in, and its smiles all around
PUA: Ill let you have my phone number. And ill let you give me yours. Just please dont give it to any other girls who ask for it.
AFC: Will you let me have your phone number?