What if she asks why after you've asked for her number?

"So I can write it on the bathroom wall."

Do you give her a real reason, move on, change topic then ask for it again. Or do you just give her some witty reply and immediately ask for it again?

u can ask her number right after u discover that the 2 of u have something in common, for example if u or she say:
i like the yankees/bulls/going to art exhibitions/going to some bar/whatever
then u said: cool give ur number so we can go somtime together

at that point u can pretty much arrange a date, just invite her like u invite ur friends and dont call it a date

also i never "ask" for her number, i always say give me, the first is asking for permission and the second one is a commad

it has never happen to me that she asks why, (wich she shouldnt if u used the example of above) but if she does ask then u can say

a) just in case i feel like taking u out, but now im having second guesses
b) just in case i feel like taking u out, u feeling lucky ?
c) so i can give it to a kidnaper raper, to take u out dumbass

its ur choice

As far as asking for someone's number never ask, tell her to give you her number it comes off as more confident. Remember your in control you already know she's gonna give you her number. (If you don't fake it until you make it.) Or hand her your phone, she should know what to do, if not tell her to put in her number.

In the chance that you do I'd be direct or witty depending on the girl. Direct if she's a harder target saying, "How else am I going to ask you out later?" or as maybe a witty I might say, "Well it's for this guy I met earlier, he was over at the bar doing shots mumbling something about breaking up with his girlfriend about 15 minutes ago, he's perfect for you... (sly smile)."

A goo one, is "I would really like to continue this sometime." Then pull out your phone and say, "Gimme your number." Firstly, your giving her a reason, a good one, which she probably shares with you (if your game is solid) and second your giving her a command, not too pushy, but just enough to work.

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Social interactions and fun, that's why I'm here.

I didn't really mean ask.

So let me rephrase.

When you tell someone to give you their number and they ask why, what would you say/do?

This doesn't happen often to me, but some replies I've used before are:

"I'm trying to see how many numbers I can get in one night, I'm currently on track to beat my record".

"Well, I was just looking forward to spamming you with hundreds of messages and calls every day."

"Oh, I think you know why".

It's all in the delivery though, if you're very calm and have a cheeky grin and/or wink then it works. Instead of being like "what? uhh, well, you know, so I can call you and stuff".

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Flowmentum Dating | FB

I'd go with the confident line: "Because I want to use it."

If I've built enough attraction, I usually just tell the girl I'll call her, and start to walk away, then she'll stop me and tell me I don't have her number. But I find it hard to pinpoint correctly all the time when he girl is at this point, and I must admit I've walked away from a few in this manner with them laughing, in a perfect mood to continue, but just not ready for that.

What I usually do is tell her through some gimmick, that I'm reading her mind, and that if I was to ask for her phone number, she'd give me a 555 number. This sets her up because depending on your emphasis and structure, you can make it feel that you wouldn't care any way, that you're not really asking for the number, and yet you give her the opportunity to correct you in a classy manner without her feeling like she's just dropping her number to "that guy in the club".