My HP32s from ~40 years ago still resides on my workbench where I mess around with RF circuits for fun. It has no graphing capability and it's barely programmable, but that's ok, I keep an actual computer nearby for those sorts of things. The calculator keeps earning new batteries bc tinkering with analog circuits I frequently want to evaluate little things like AB/(A+B) or 1/2piF or (1+S)/(1-S), or need the log 10 or square root or the cosine of something.

In those circumstances, the calculator's compact form factor is quite convenient, compared to needing two hands at the computer keyboard, or one handedly hunt-pecking said keyboard. As for the mouse, that has to be the slowest, most focus stealing option of them all. The calculator doesn't take much room, so it can be kept within arm's reach without getting in the way, quickly gives me the numbers I need, without demanding I become fully engaged with it.

Also, those old HP buttons are just so nice to press, a refreshing break from the dead flat glass you get everywhere else these days.