On Wed, 19 Jul 2006, Dan Drake wrote: > I'm teaching a math course for elementary school teachers, and today we > told them about Reverse Polish Notation, just to make them think about > order of arithmetic operations. > > It would be nice to actually own an RPN calculator, so one could show > students that this isn't just an abstract curiosity. Does anyone have an > old RPN calculator that they would sell me, or know where I could get > one? It's been a long time, but I worked selling calculators in a store 30 years ago! I'm pretty sure that RPN was the approach taken on all HP calculators, but I guess that changed over the years. Here's an excellent web page: http://www.hp.com/calculators/news/rpn.html It provides a little web-based calculator that you can use to practice RPN. Mike