I am a decidedly non-mathematical/non-engineering person, but have loved RPN calculators since I bought an HP back in the mid-1970s. RPN is just natural to me,

I am a decidedly non-mathematical/non-engineering person, but have loved RPN calculators since I bought an HP back in the mid-1970s. RPN is just natural to me, even doing basic arithmetic. I use PCalc in RPN mode on my iPhone.