kcalc from kde gives a simple calculator that supports science and hex calculations

X48 is a Hewlett Packard scientific calculators that can be get by emerge x48. Type man x48 or checkout https://sourceforge.net/projects/x48.berlios/ to get help.

An other alternative is be nonpareil see: http://nonpareil.brouhaha.com/

It is a collection of older Hewlett Packard models and includes the HP41.

The program will be put into /usr/local/bin instead of selecting the model using a gui, nonpareil can be called as nonpareil --shape <prefix>/lib/nonpareil/41cv.kml to open directly a calculator. The default prefix is /usr/local but Gentoo Linux requires /usr . kml files are text files that define microcode, image, keys.

For the old HP calculators there is also the HP museum where manuals (unfortunately not free) and all kinds of other stuff can be found: http://www.hpmuseum.org/

There is also a HP-35 (JavaScript) that can be opened in any browser when Java is enabled.

There is also emerge free42 that can be started with free42dec. It comes with a nice looking realistic skin but can also be switched to an ugly skin.

Last but not least type man bc to see about the console calculator.

Or use wine and install the windows hp41 emulator from www.hp41.org .

To have a nice calculator having hex support emerge calculator