The trick to being a math major is learning how to make a formula sheet. Some professors will allow you to bring a formula sheet with what ever you want on it and this is the goddamn greatest thing ever. I spent 6 hours working on this glorious piece of art. I want to frame it. It has everything I could possibly think of with room to spare!
For an even better version of this, you could scan your formula sheet, shrink it down and then write more in the margins. Or, if your professor only lets you write on one side, you could try making a moebius strip! That way you can tell your professor that it’s one sided (while having written on both sides). Results may vary on that one though.