Found my old grade school calculator while going through some drawers. It’s not programmable or retro (yet) or valuable, but it served me well for many, many years.
Pretty sure I learned the pattern for incrementing binary numbers on this thing while I was sitting bored in study hall before I even knew what binary was.
That is definitely a well used little device! Coincidentally, the last calculator that I bought a couple of months ago is the EL-501X2, the most recent iteration of the model. Not a bad little calculator as long as you stay away from the edge cases! The edge cases are where the fun stuff is for me, cause I really like finding out where these machines tip over.