Finished with my calculator today and tested it on my galaxy tab.  Seemed to work fine.  Actually, found some bugs.  Hard to believe there were bugs in a simple calculator but there were.  In any case, all fixed now.   Now for creating the endless stream of icons that you need to publish to iTunes and Google play.  I don't understand why I can't just give them one big image and have them pragmatically create all the other sizes they need.  But oh well,  another day making icons wont kill me.