HP's RPN calcs were ubiquitous in the 1980's .. especially the HP 41c. If you didn't have one for your physics exam you were at a clear disadvantage. I never kn

HP's RPN calcs were ubiquitous in the 1980's .. especially the HP 41c. If you didn't have one for your physics exam you were at a clear disadvantage. I never know why folks quit using them. I still have mine and can kick anyone's tail with a infix calculator. In fact, when I was a professor, I would challenge all the students in the class to see if anyone could be beat in evaluating a large expression. I would write a gnarly expression on the board as a challenge. No one was even close to me. Parentheses are for the weak and slow.