When he tries that number and gets a random person, he'll probably flip you the middle digit.

he's probably going to write a fml as well saying he was given the wrong number by someone he thought he had a connection with

Next time, let him write an sms to himself from yours.

If you remember how exactly you mixed the numbers you may try to call the person and ask them nicely to give your number to the guy when he calls. No guarantee that the owner of the number will do as you ask, but worth trying.

It depends upon how keen he is, only 120 to 1000 combinations depending on whether any of the middle three digits was the right number but in the wrong place.

He's not gonna know it's the middle digits though is he?

See, that's one thing that couldn't happen to me. a), I don't like bars etc so I'll probably never be asked for my number anyway, and b), I don't have it memorized and thus need to look it up when I give it to someone. At least something that'd be useful for.

Let me play you a song on the world smallest violin

Congratulations. Would you like a medal?

Go back to said bar and see if you run into him again. Maybe luck will be on your side.

Text the number you accidentally gave him, briefly explain and ask if they can please send him your way (the correct number) if he texts them. :)

I've bever understood this. I thought it was common practice to dial the number once after it's been given to you to make sure you got it right. That way if there's a problem it can be fixed on the spot