+COFF On 3/20/20 8:03 AM, Noel Chiappa wrote: I'm sure that there are some people, maybe not the corpus you mention, that have zero clue how an RPN calculator works. But I would expect anybody with a little gumption to be able to poke a few buttons and probably figure out the basic operation, or, ask if they are genuinely confused. I agree that RPN is not rocket science. And for basic single operation equations, I think that it's largely interchangeable with infix notation. However, my experience is, as the number of operations goes up, RPN can become more difficult to use. This is likely a mental shortcoming on my part. But it is something that does take tractable mental effort for me to do. For example, let's start with Pythagorean Theorem a² + b² = c² This is relatively easy to enter in infix notation on a typical scientific calculator. However, I have to stop and think about how to enter this on an RPN calculator. I'll take a swing at this, but I might get it wrong, and I don't have anything handy to test at the moment. [a] [enter] [a] [enter] [multiply] [b] [enter] [b] [enter] [multiply] [add] [square root] # to solve for c (12 keys) Conversely infix notation for comparison. [a] [square] [plus] [b] [square] [square root] (6 keys) As I type this, I realize that I'm using higher order operations (square) in infix than I am in RPN. But that probably speaks to my ignorance of RPN. I also realize that this equation does a poor job at demonstrating what I'm trying to convey. — Or perhaps what I'm trying to convey is incorrect. — I had to arrange sub-different parts of the equation so that their results ended up together on the stack for them to be the targets of the operation. I believe this (re)arrangement of the equation is where most of my mental load / objection comes from with RPN. I feel like I have to process the equation before I can tell the calculator to compute the result for me. I don't feel like I have this burden with infix notation. Aside: I firmly believe that computers are supposed to do our bidding, not the other way around. s/computers/calculators/ I'm confident that 80% of people, more of the corpus you describe, could use an RPN calculator to do simple equations. But I would not be surprised if many found that the re-arrangement of equations to being RPN friendly would simply forego the RPN calculator for simpler arithmetic operations. I think some of it is a mental question: Which has more mental load, doing the annoying arithmetic or re-arranging to use RPN. I believe that for the simpler of the arithmetic operations, RPN is going to be more difficult. All of this being said, I'd love to have someone lay out points and / or counterpoints to my understanding. -- Grant. . . . unix || die