Life is a Mind Bending Puzzle

These are all models that have some sentimental value for me either because I used to have one or because I wanted one. Rockwell 44RD: This was my first scientific calculator. I think the colour scheme and VFD display still look great. https://www.calculator.org/calculators/Rockwell_44RD.html HP 15C: This was the calculator that every student engineer in the 1980's wanted but I couldn't afford one so I used a succession of cheaper calculators instead. I have no interest in one of the remakes. I would like to own a 1980s original. https://www.calculator.org/calculators/Hewlett-Packard_HP_15C.html Casio FX-7000G: When I finally started earning my head was turned by the latest graphical calculator from Casio. It was big and awkward and had poor battery life. I probably should have gotten a HP15c instead. I would still like a 7000G for nostalgia's sake. https://www.calculator.org/calculators/Casio_fx-7000G.html Casio FX115D Super FX. My FX 7000G was stolen and I replaced it wit...

 About a year ago I changed from a person who owns a few calculators into someone who collects them.  Scientific calculators that is. It has not become an obsession yet but I spend a fair amount on time on r/calculators and drop into second hand shops regularly to see if they have any old models.  For what it is worth here is my current collection:  My Casio models in order of age are shown above. Casio is the most common brand in Ireland and I have owned and used many over the years. Noticeable models include an FX9860GII which is a very nice programmable graphing model from 2009 and an FX991CW+ 2nd Edition UK which is Casio's latest "A-level" model. This is a do-over of Casio's disastrous (in my opinion) FX991CW released in 2023. Casio is to be praised for still innovating in the calculator space but it beggars belief that they released a scientific calculator that had somehow forgotten how to use scientific notation. Thankfully the 2026 2nd edition models have fix...