Musings and comments about our common interest
One of the things you need in business (be it finance or engineering) is to be able to use your formulae in a solver environment.
The HP Prime can allow just 10 different formulae in the Solver app. You need to select them one by one, de-selecting the rest, lest you want to have all solved at the same time (and if not done properly the calculator will protest). But in any case, you have a hard limit of then formulae.
But then, it comes the "save" feature. You can save an app with a different name, and then you can have a set of different solver apps, each with a different name, indicative of the formulae in it; for example, business comparisons, where you can put mark-up, margin, increase and total. Or, in other area, you can put the electrical identities - ohm's law, etc. Then you can have as many formulae as needed.
This solver allows for good visibility of all variables at the same time. You can navigate among them with your fingers, instead of circling around them with the arrow keys, or through several ENETER presses. A most useful feature!!