For whatever reason my high school had HP48s for my junior year math class, which got replaced the following year for TIs since “that’s what you’ll be using in college”. I much preferred the RPN and ended up convincing my parents my life would be easier with a new HP49g (which wasn’t a lie, it was). That thing helped get me through my math major and I’ll always remember my old school professor who taught my complex analysis course amazed that it could even solve those equations (which I’m sure the TIs could do as well).
With the GX (which I got, and it still works) you could run metakernel [0], which itself was one heck of an upgrade over the base system and really an unbelievably impressive effort in its own right. It pushed the hardware so much farther it's still stunning. The HP48 remains one of my favorite calculation devices ever, with a great ratio of utility for both the most simple brainstorming calculations and going right into great depth. I'm still bummed my favorite emulator for iOS devices (m48+) stopped getting updates and faded away, and also that HP let its calculator division languish. What a tool.
