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Comment by andi999 | Hacker News Reader

Standard mode doesn't follow PEMDAS. This software needs to go.

https://answers.microsoft.com/en-us/windows/forum/apps_windo...

This is the standard way calculators have operated since forever. They don't evaluate a whole expression, they simply have an accumulator and you operate on it one step at a time.

Still, it's surprising that this behavior changes when you switch to "scientific" mode. The UI doesn't communicate it well.

Never had such a calculator, but probably you are right.

You’ve never used a cheap four function calculator?

It's probably a concession to skeuomorphism. Most physical calculators I've seen that look like the standard mode ignore PEMDAS as well, whereas pretty much all scientific calculators will respect PEMDAS.

If you took one of the people who still use old fashioned "standard" calculators and put them on a standard mode that followed PEMDAS, they'd probably be confused, at least initially. I've seen that a lot at cash registers in restaurants, dry cleaners, and other small businesses.

Actually my hunch is the microchip doesn't need a stack then, so is cheaper.

While its basic math you would be surprised at how many people have forgotten about PEMDAS. I would argue that the additive way comes more naturally to people. For people wanting to more complex equations scientific one does follow PEMDAS.

I think it's just a matter of people adapting to the tools that are easily available. Almost 100% of the time I've seen someone use an actual basic tabletop calculator, they've been tallying prices and slapping on a sales tax. At that point it's just a learned ritual and they're not thinking about order of operations. If they needed parentheses, they'd just memorize that the parentheses go around the prices.

Once the computations get complex enough that you have to write down the formulas, then it makes a lot of sense to treat the computations as algebraic expressions, meaning PEMDAS.

Personally I've always found relying on operator precedence uncomfortable and usually add always parenthesis even when they are not strictly needed, this was the case even back in high school when we were doing calculations with then fancy graphing calculators. I just find the extra degree of confidence worth the slight extra effort and noise. Maybe I'm just a belt and suspenders type of guy.

These days for actual physical calculators, and on phone, I've transitioned to RPN which neatly transcends such petty ambiguity problems.

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