If you can't handle a no and aren't certain you won't get one, you shouldn't be asking. I wish everyone actually understood and followed that rule

Sorry but what is DA?

This sounds like a good strategy for when you want to actually give the guy your number. See how he responds and if he's like this guy, say "Wait, I changed my mind." A nice little pre qualifier.

I don't remember where from, but someone suggested society should switch to offering numbers instead, and I love it.

Someone offers you their number, you save it if you want, when you get home it's still YOUR choice to send the first message.

If you don't, your number won't show up on their phone, and they can't message you. It's genius