I was one of these smug HP calculator owners back in high school and college. I loved it and spent hours hacking on it (and also secretly enjoyed the fact that nobody borrowed it since hardly anyone knew how to use it).

Years later, I started realizing that the reason why these calculators do take fewer keypresses to make calculations is because they borrow your brain to assist them.

For example, you see `3 * (2 + 4)` and your brain has to identify the most nested parenthesis expression, type that in and work your way out. It works well enough for simple expressions but doesn't really scale very far beyond that.

Remember this SETI program that used people's idle CPU's to scan sky pictures? I felt HP calculators had been pulling the same trick by borrowing your brain to calculate their expressions.

I felt that I had been cheated but I wasn't really mad about it because I loved these calculators so much.

edit: 42S not 42C

When you encounter an open parenthesis, then you just push the following number onto the stack, when you encounter a close parenthesis, you just perform the relevant arithmetic operation.

For the example

    2 * (3 + 4)

    Input            Stack
    2                   2
    3                   3,2
    4                   4,3,2
    +                   7,2
    *                   14

    2 * (3 + (4 + (5 + (6 + 7))

    6 7 + 5 + 4 + 3 + 2 *

Expand this expression with multiple deeply nested parens and the limitations of RPN become very obvious.

4 is usually enough in practice anyway. Your example is artificial.

Besides, are you sure your infix calculator will accept this deep a nesting of parentheses? The TI models that were contemporary with the early HPs certainly wouldn't!

Of course, you're comparing the HP41C to bad infix calculators, early ones that didn't support algebraic order of operations or explicit parentheses.

It's worth remembering that postfix calculators exist not because they were ever the right thing to do, but because they were easier to implement with limited computing power. Forcing the user to keep track of the stack context was a clever hack on HP's part, but is no longer necessary or justifiable. And that's why you don't see many new postfix calculators these days.

Closest thing I can recall was the contest that pitted a texting teenager against an experienced ham radio operator with a telegraph key...

In all my life I've only ever seen two HP RPN calculators. One belonged to my high-school chem teacher, the other to a real estate agent. If there were a $30 RPN calculator with similar functions, I would use it.

Edit: 18 years later and they still make it, https://www.casio.com/products/calculators/fraction-and-scie...

Edit2: Looks like the most readily available RPN calculators are the HP 35S ($55) and HP 12C ($50).

I don't get it either. Even if HP lost interest, why didn't anyone continue with RPN (patents, maybe?).

I think RPN is both better for learning at school (you see intermediates, and you learn operator order), as well as general use. I love that you can just get stuck in calculating without having to worry about getting it all in the right order at first.

I'd love my children to use RPN when they reach that age, but there is a lack of RPN calculators on the market, a lack of knowledge at school and it may even be banned by the time they need to take an exam.

Even better if I don't have to worry about it at all. That's why I'm using a calculator in the first place, and not scribbling figures by hand on a piece of paper.