I learned RPN as a college freshman studying engineering in the late 1980's. Almost all of my fellow students had HP RPN calculators. Once we where doing more a

I learned RPN as a college freshman studying engineering in the late 1980's. Almost all of my fellow students had HP RPN calculators. Once we where doing more advanced math RPN -- with the accompanying stack -- became so much easier to enter. We all quickly learned it and I think most of us came to hate standard calculators.