I know I'm dating myself here (hold the masturbation jokes, please) but until this past week, I hadn't used a scientific calculator since the late 80's. And back then, any function (x2, cos x, sin x, etc etc etc) would get instantly applied to whatever number was showing in the calculator display the second you pushed the button - so 3/4 the work of any given moderately complex problem was breaking it into steps with no more than a single function operation at a time, storing the result of that in memory, setting up your next step, recalling the memory at the appropriate point in that operation, storing THAT one... lather, rinse, repeat.
So when I first started using my new ($16!) TI-30x IIS, it confused me a little at first - 'cause I'd find the number I wanted to take SIN of, then hit SIN. And, y'know, instead of taking the SIN of whatever the result of my last operation was... it would just stick SIN( in the window AFTER that number. And then I realized... OMFGOMFGOMFGHOLYCRAP. If I want to find the hypoteneuse of a right triangle with 2cm and 6cm legs, I can just enter in SQR(22+62) and hit = and IT WORKS. NO INTERMEDIARY STEPS.
I know most of you either take this completely for granted or never use a scientific calculator for anything to begin with and therefore don't know/care what the fuss is about... but holy GOD this is great. If this calculator had the appropriate orifice(s), I would seriously consider living in sin with it.
(As things stand, I'll probably just stick to math homework. Which I should go do now.)