I still find using hardware calculators for brainstorming, field calculations and cross checking my software faster than using RealCalc on my phone or software calculators on the PC, except when I have to transfer numbers often to another app for further evaluation.
When US schools went on summer break, Walmart and Amazon dumped inventory on the Casio FX260 for $6, FS-115ES [ called FS-991-ES elsewhere] For $11 and the TI-36XPro for $18. I picked up a few Casios and a TI.
The last two are staples in US colleges for math and engineering courses. They can do definite integrals, polynomials, expression evaluation and much more, have been around for nearly 15 years [ as prior model, without 'ES' for Casio or Pro for TI] and have been reviewed extensively by many for strenghts and weaknesses.
I've never liked the first version of VPAM and wrote such calculators off for many years. But the updated 'VPAM' or textbook displays look very much like you'd write on paper and make entering fairly complex equations into these calculators easier.
Graduates of colleges >=15 years are likely seasoned veterans of these calculators but those of us who were in school before that will find these capabilities another timesaver worth a look, given the cost of these calculators.
There are also 2 other competing units with a similar breath of functions from Sharp and Canon, but they cost more and can be hard to find. Casio and TI are the leaders in the education fields worldwide and one reason [ if not the only reason] these calculators are still made or so cheap.