I'm in the process of developing an Android-friendly version of FermCalc. You can download a test version of the apk file here. I'll eventually post it on Google Play, but before then I'd like to get feedback on it from other users since I've only tested it on my Android tablet and on some emulators. Use the feedback link at the bottom of the main menu to report any issues, to suggest improvements, or just to let me know how it's working for you. Thanks in advance for your suggestions. Enjoy!