I've noticed that people who rely on calculators have great difficulty recognizing when their answers are off by a factor of 10.
I know a hiring manager who asks his (engineering) candidates what is 20% of 20,000? It's amazing how many engineers are completely unable to do this without a calculator. He said they often cry. Of course, they're all "no hire".
100% Agreed. There is genuine value in occasionally performing things the "manual way", if for nothing else then to help develop a mental intuition for figures that might seem off.
This is a sort of mental math trick that isn’t incredibly useful in day to day engineering. Now if they say 16,000 or something then maybe there’s an argument against them, but being able to calculate a tip on the fly isn’t really something worth selecting for imo
And yes, it's incredibly useful in enabling recognizing when your calculator gives a bogus result because you made a keyboarding error. When you've got zero feel for numbers, you're going to make bad engineering decisions. You'll also get screwed by car dealers every time, and contractors. You won't know how far you can go with the gas in your tank.
It goes on and on.
Calculators are great for getting an exact final answer. But you'd better already know approximately what the answer should be.
> it's incredibly useful in enabling recognizing when your calculator
gives a bogus result because you made a keyboarding error.
Humans are much better at pattern matching than computation, so the
safest solution is probably to just double check if you've typed in the
right numbers.
> recognizing when your calculator gives a bogus result because you made a keyboarding error
It might be counterintuitive, but the cheaper (and therefore successful) solution will always be more technological integration, not less.
In this case, better speech recognition, so the user doesn't have to type the numbers anymore, and an LLM middleman that's aware of the real-world context of the question, so the user can be asked if he's sure about the number before it gets passed to the calculator.
I don't know if this is a trick but the fast way I did that problem quickly in my head is 20% = (10% X 2) i.e calc 10% of the number then double it.
To quickly calc 10% just multiply the number by 0.1 which you can do by moving the decimal point one place 20,000.00 => 2,000.000 then it is easy to double that number.
For me, it's just that 20% is one fifth. One fifth of 20 is 4 and you add the remaining zeroes.
You mostly have common equivalences like this in your memory and you can be faster than computing the actual thing with arithmetic. Or have good approximations.
I know a hiring manager who asks his (engineering) candidates what is 20% of 20,000? It's amazing how many engineers are completely unable to do this without a calculator. He said they often cry. Of course, they're all "no hire".
How did they get a degree, one wonders?