How to ask a guy for his number?

Okay so I don't believe in the Un written rule that guys have to do everything first lol. (i'm 15) I've gone to 4 football games and met cute guys and then they don't ask me for my number so I ask them. And I texted all of them right after I got it to say "hey it's Gabrielle" and none of them text back. Like all they have to say is k got your number. Or something! But none of did & one did reply and said he thinks I have the wrong number haha. So is it that i'm asking them the wrong way? Or I'm not pretty enough? Or popular enough? Or what is it? & PART 2 OF QUESTION: I dm'ed this guy on Instagram he seems so nice so I DMED him (direct message) asking for his number and he replied saying well do you have an iPhone? And I replied yeah. And he never replied. I think it's because he didn't see it because it doesn't tell you if you have a message on there, you manually have to go in and check. So should I DM him again and say like hey, you never gave me your number or heh what's your number? Or should I just drop it and move on? SORRY SUCH A LONG THING BUT Please Help ME ON BOTH SITUATIONS AND Thank you So MUCH TO EVERYONE WHO ANSWERS!

Tell him that you wanna stalk him for Halloween.

Haha honestly just ask him in front of his friends then he'll have to say yes and you'll make him look good in front of his friends or just ask him casually or even give your number to him like say hey we should talk more here's my number

No reason a girl can't ask a guy for his number, however there's also nothing that says a guy has to respond.

Back off a little, sounds like you are being way to aggressive.