Not a mathematician but last year I needed to do some serious (for me) math at short notice (api provider for some complex calcs dropped us in it) and sagemath with ipython notebook saved me as I could convert all the formulas into python and then inspect and graph the output to give me an idea of what was going on, if I'd have had that at school I think I'd have been way better at math the ability to 'play' with formulae is incredibly powerful.