This app was mentioned in 7 comments, with an average of 1.86 upvotes
> replacing built in calculator
Yeah, who'd want to do that
considering most people have smartphones now, how about phone app?
there is excellent HP 42s app for both ios and android:
https://apps.apple.com/app/id337692629
https://play.google.com/store/apps/details?id=com.thomasokken.free42
... but there are many more, including ones with 3d graphing etc
Check out the 48 when your 42 dies Or check out the free42 for android https://play.google.com/store/apps/details?id=com.thomasokken.free42&feature=also_installed
free42: you underestimate my power
Free42 has all those features and only lacks those lovely old HP clicky buttons.