Ok, so I saw a cage today online that was over 50 square feet! According to the rat calculator, 21 rats can fit in it! Like any lover of rats I started fantacizing about things I could do with the cage; keeping all of Marsha's babies, having a colony of rats...but then something interupted my day dream. Is there a limit? How many rats can you keep in one cage, no matter how big it is? I mean just because you have a cage as big as the moon doesn't mean you can keep a billion rats in it...does it?