I have been using Auditor Calculator as a windows calc replacement for years. I have been using it installed on my PortableApps drive for several months now and it works like a champ. It basically mimics a desktop business calculator and even has a tape that you can print out or copy to the clipborad.
I have been using it installed on my PortableApps drive for several months now and it works like a champ. It would be a nice addition to the PortableApps collection.
The only license I can find only says FREE. The web site for it is: http://www.auditor2000.co.il/aucalcdl.htm . This page is in english but most of the site is NOT. They are based out of Tel-Aviv, Isreal.
Auditor is not Open Source, but I've found it to be natively portable, being dependent on only msvbvm60.dll. If you want to include Auditor in your PAM items, just place the Auditor directory inside the PortableApps directory as a subdirectory. PAM should pick it up automatically.
It is technically portable but it writes settings to the registry. Therefore would need a portableapps launcher or that to be truly portable. Can I suggest you take a look at speed crunch. Ive been using it for a while now and found its extremely useful. Give it a go. its an official app too so its been test and proven to work already as well.
Enjoy : )