Does a SIM have a number?

Does a SIM have a number? Well, duh! Mine does, anyway. It's this long, kinda crazy number – thirteen digits, I think? Sometimes there's a letter tacked onto the end, and I'm never quite sure what that's all about. It feels like a secret code for my phone, you know? Like, only my phone gets this special number.

I've had to give it out a few times – filling out online forms for my carrier, that sort of thing. And sometimes they only want the numbers, not that weird letter at the end, which is fine by me! Less to remember, ha! But yeah, it's definitely important. It’s connected to my account and everything, so I try to keep it safe, like tucked away in my password manager. Imagine losing that number… what a nightmare that would be! I remember once, my friend Sarah lost hers and had to go through all this hassle to get a new one. It was a whole thing. So, yeah, little piece of plastic, big important number.