I used to use a TI-83+, but now I've gotten into the habit of opening a Python or Node.js REPL for math. That way, I can copy-paste values to and from emails or chat. It also helps that I already know the syntax and math libs.

I tried bc[1] as well, but it has some really annoying defaults. For example: While it's capable of arbitrary precision, it calculates out to zero decimal places unless you tell it otherwise.

1. https://www.gnu.org/software/bc/

I've tried that but for me a REPL for calculating occupies an annoying middle ground: not as efficient as a calculator for quick calculations and not as powerful as say MathCAD for exploratory work. IPython's a step in the right direction.

I always start it as "bc -l". On some computers I have alias bc to that option.

Emacs calc is convenient and very full featured to say the least

I keep using sometimes my old Casio FX-85MS . I only need to change the power cell one time in all this years since I bought like 12 years ago

Knobs are awesome. I lament their passing in eg car radio and car aircon UI, and in microwaves.

Pilots lament their passing in the cockpit. Plenty of readings and buttons that were available instantly are now only available after the perusal of menus used to multiplex a single display or button across many readings or actuators.