7 ms·

That’s funny because when I work with Fahrenheit I just work with 5°F ranges to compensate for the approximate mental math required. Eg very quick mentally, 100

That’s funny because when I work with Fahrenheit I just work with 5°F ranges to compensate for the approximate mental math required. Eg very quick mentally, 100°F = 37.778 °C (thanks autocorrect) = (100-32)/2 = 34. But if it was closer to freezing say 42°F =5.556 °C (again) so 5°C. So arbitrarily we could say 57°F was 12°C =53.6 °F actually. But a true Canuck knows knowing the temp is barely half the battle, what’s the wind speed and humidity? 29°C can be a lovely day if it’s dry or completely unbearable if it’s humid. We hardly ever use decimals for weather-related measurements, the other factors above being more relevant. Contrast that with measurements where I would say if you need to know a precise one you should be using decimal; ie what do you do if it doesn’t precisely third or fourth? If you’re talking about tool sizes then any system works as long as your froodle matches the grommlet.

candiddevmike 8mo ago
(F - 30) / 2 = ~C C * 2 + 30 = ~F
- SECProto 8mo ago
  No need to simplify this. (F - 32) / 1.8 = C C * 1.8 + 32 = F I personally find the math just as easy to do accurately. For example, 87F -32/1.8 = 55/1.8 =~30.5C. Compare that to your approximate method, which would give 28.5C, which is just wrong (Maybe I just got really good at this when working a public facing job with a lot of American tourists - they would ask what our celsius temperatures were "in real units", so I got quite comfortable converting the air and water temps. Fahrenheit never once became intuitive to me, though.)
  - tzs 8mo ago
    For C to F you can often simplify the mental math by doing the multiply by doubling then taking off 10%. E.g., to convert 31℃ to ℉: 31 x 2 = 62. Subtract 6.2 = 55.8. Add 32 = 87.8℉. If you want to round the result to the nearest integer the subtract 10% step is a convenient place: 31 x 2 = 62. Subtract 6 (rounded 6.2) = 56. Add 32 = 88℉.
    - SECProto 8mo ago
      Yes, doubling then subtracting 10% of the resultant works because that is the same as multiplying by 1.8 :) When going the other way and dividing, I similarly find it mentally easier to multiply by 10/18 (rather than just divide by 1.8)
- bsder 8mo ago
  (F + 40) * 5/9 - 40 = C (C + 40) * 9/5 - 40 = F Takes advantage of the fact that -40 F and -40 C are the same. Remember it as (move origin -- convert -- move origin back). I find it easier as a I don't have to remember precedence rules and the multiplication is obvious.

candiddevmike 8mo ago

(F - 30) / 2 = ~C C * 2 + 30 = ~F

SECProto 8mo ago
No need to simplify this. (F - 32) / 1.8 = C C * 1.8 + 32 = F I personally find the math just as easy to do accurately. For example, 87F -32/1.8 = 55/1.8 =~30.5C. Compare that to your approximate method, which would give 28.5C, which is just wrong (Maybe I just got really good at this when working a public facing job with a lot of American tourists - they would ask what our celsius temperatures were "in real units", so I got quite comfortable converting the air and water temps. Fahrenheit never once became intuitive to me, though.)
- tzs 8mo ago
  For C to F you can often simplify the mental math by doing the multiply by doubling then taking off 10%. E.g., to convert 31℃ to ℉: 31 x 2 = 62. Subtract 6.2 = 55.8. Add 32 = 87.8℉. If you want to round the result to the nearest integer the subtract 10% step is a convenient place: 31 x 2 = 62. Subtract 6 (rounded 6.2) = 56. Add 32 = 88℉.
  - SECProto 8mo ago
    Yes, doubling then subtracting 10% of the resultant works because that is the same as multiplying by 1.8 :) When going the other way and dividing, I similarly find it mentally easier to multiply by 10/18 (rather than just divide by 1.8)
bsder 8mo ago
(F + 40) * 5/9 - 40 = C (C + 40) * 9/5 - 40 = F Takes advantage of the fact that -40 F and -40 C are the same. Remember it as (move origin -- convert -- move origin back). I find it easier as a I don't have to remember precedence rules and the multiplication is obvious.