IMHO keeping stacks and stacks of composition books can't be beat. Seriously. You can flip through them to remember stuff or see what you did. I only use notebooks and pen when doing math. Pen keeps you from erasing your mistakes and remember them as well. I'm also a very heavy proponent of going digital when possible,all my recreational reading books are digital,I have a beefy cell phone, tablet,laptop and desktop I use all for different things whenever I can,but I still firmly believe nothing beats notebooks for math, PERIOD. If you're using something else like mathmatica as well, print things out and place the prints in your notebook. I prefer drawing myself. Get a tablet to organize yourself and your schedules, but use paper for scratch paper.
---------- Post added at 11:07 PM ---------- Previous post was at 11:00 PM ----------
If you're merely trying to justify the purchasing of a tablet, just buy the dang thing, you'll use it, tablets are awesome, unique and convenient technology