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This would have made my college career significantly easier. We were limited on scratch paper (dumb policy) on many tests, and I have to write out arithmetic li

This would have made my college career significantly easier. We were limited on scratch paper (dumb policy) on many tests, and I have to write out arithmetic like this long-hand style, which took up a ton of space.

deleted 2y ago
[deleted]
bee_rider 2y ago
I think these sort of mental math tricks are mostly useful when you have a case where you’ve got a formula that you often have to run, and it is similar enough every time that you can pre-do the algebra. The one everyone knows is calculating a tip (bump the decimal place left once and double the result, round depending on how nice you feel). Might be applied multiple times per day, depending on your dining habits. I bet the formulae you had to use on your tests were worth doing by hand.
- JohnMakin 2y ago
  They weren't formulae - it was literal arithmetic. Complete waste of time and space.
- laurentlb 2y ago
  My formula for calculating a tip is `return 0`, but it's very country-dependant. (US-defaultism?)
  - spookie 2y ago
    You may tip anywhere you find the service pleasant. (EU guy who has worked as a waiter)
akovaski 2y ago
I recently leafed through "Mathematics for Engineers"[0], originally from 1926, which begins with many such methods for making arithmetic easier. Though maybe not always more space efficient. Luckily I got to use a calculator for school. [0]https://archive.org/details/dli.ernet.11725/page/n9/mode/1up https://archive.org/details/dli.ernet.11725/page/n9/mode/1up
hinkley 2y ago
If you look at the way they teach kids math on paper today, they are just teaching them how to do math in your head. The idea being that if your hands were free you’d use the calculator on your phone. When I first encountered the outrage over New Math my first thought was that this is how I avoid embarrassing myself in checkout lines. Do I have enough cash to pay for this stuff in my hands?

deleted 2y ago

[deleted]

bee_rider 2y ago

I think these sort of mental math tricks are mostly useful when you have a case where you’ve got a formula that you often have to run, and it is similar enough every time that you can pre-do the algebra. The one everyone knows is calculating a tip (bump the decimal place left once and double the result, round depending on how nice you feel). Might be applied multiple times per day, depending on your dining habits. I bet the formulae you had to use on your tests were worth doing by hand.

JohnMakin 2y ago
They weren't formulae - it was literal arithmetic. Complete waste of time and space.
laurentlb 2y ago
My formula for calculating a tip is `return 0`, but it's very country-dependant. (US-defaultism?)
- spookie 2y ago
  You may tip anywhere you find the service pleasant. (EU guy who has worked as a waiter)

akovaski 2y ago

I recently leafed through "Mathematics for Engineers"[0], originally from 1926, which begins with many such methods for making arithmetic easier. Though maybe not always more space efficient. Luckily I got to use a calculator for school. [0]https://archive.org/details/dli.ernet.11725/page/n9/mode/1up https://archive.org/details/dli.ernet.11725/page/n9/mode/1up

hinkley 2y ago

If you look at the way they teach kids math on paper today, they are just teaching them how to do math in your head. The idea being that if your hands were free you’d use the calculator on your phone. When I first encountered the outrage over New Math my first thought was that this is how I avoid embarrassing myself in checkout lines. Do I have enough cash to pay for this stuff in my hands?