RPN

If you arre an aging computer nerd like me, you probably have always preferred RPN calculators over algebraic calculators (the kind with an = sign).  Perhaps it is just being a rapscallion or the result of writing arithmetic parsers in computer science classes (where RPN really matters).  Or maybe it's just my weirdness.  But while my wife was paying a mental health visit to a thrift store, I was trying to use an algebraic calculator on my phone called PowerCalc to calculate joules of energy delivered by projectiles at near-light speed.  In frustration, I downloaded an app called RPN Calculator which was quite reminiscent of my long departed HP 45, except for lacking the EEX button for entering scientific notation numbers.