I was pretty delighted to realize I could now delete the lame Calculator.app from my iPhone and replace it with something of my choice. For now I've settled on NumWorks, which is apparently an emulator of a modern upstart physical graphing calc that has made some inroads into schools. And of course, you can make a Control Center button to launch an app, so that's what I did.

Honestly, the main beef I have with Calculator.app is that on a screen this big, I ought to be able to see several previous calculations and scroll up if needed. I don't want an exact replica of a 1990s 4-function calculator like the default is (ok, it has more digits and the ability to paste, but besides that, adds almost nothing).

I looked at that calculator. But HP Prime and TI-89 have CAS systems that can do symbolic math, so I prefer to emulate them.