buying it turned out to be one of the single best decisions of my life. it's an extraordinary little calculator. the design is exceptional - the laptop-style screen saved me hours and hours of craning my neck to peer at a tiny display. i was able to just sit back with the screen comfortably in view at whatever angle i needed, which is a very, very big deal when you've lived with chronic pain your entire life, like me. a design so much better than everything else on the market should have caught on. instead, it faded away as a footnote - the Slim is no longer made and has no successors.
importantly, the Slim has a built-in computer algebra system. which ended up carrying me through three or four math classes i really didn't deserve to pass - i have dyscalculia and solving a algebraic equations is brain-shatteringly hard, even *physically painful* for me. and it was completely impossible until my amazingly patient and all-around angelic high school algebra teacher Ms. Lytton (who was a literal rocket scientist - lovely woman, brilliant, couldn't manage a classroom to save her life) sat down with me after school and spent three hours helping me through the process until it finally clicked.
so every time i had a "solve for x" question on my homework i'd just punch the equation into the calculator and it would immediately spit out the answer. i literally would have failed multiple classes without this thing.
(it's also how i was able to cheat on the SAT and the ACT. the other important thing about the Slim is that it's very, very obscure. as in, test proctors have never seen one before and it's nowhere to be found on their "do not allow" list. despite the computer algebra system, which i was very much not supposed to have. so i didn't completely fail the math sections and managed to make it into college. which i dropped out of anyway. so, eh.)