It's been theorized that Case Math is the only form of math that's actually worth two fucks.
*you and Alex quickly perform some mental case math and both deduce quickly that each guy gets 10 beers*
*Ed is trying to give a girl a beer out of the shared case, in hopes of getting her drunk and hooking up with her.*
Ed: Hey, I'm gonna give this girl a beer from our case, cool?
You: Sure, but that comes out of your beers, me and Alex are still drinking our 10. And you'd better close, too.