I remember being confronted with an HP calculator for the first time in college. I understood RPN just fine and knew that I wanted to do, e.g., 6 7 ×, but turni

I remember being confronted with an HP calculator for the first time in college. I understood RPN just fine and knew that I wanted to do, e.g., 6 7 ×, but turning that into actual keystrokes on the calculator was not immediately obvious. I think I ended up doing something like 6 ⎆ 7 ⎆ × ⎆ instead of 6 ⎆ 7 × and got the understandable garbage result. I ended up doing a big chunk of my freshman physics homework doing the math by hand because I didn't own a suitable calculator.