Quote Originally Posted by ebb View Post
EXAMPLE:
In tech school we were required to learn this and also conversion to Kelvin and Rankin. And we had to learn that and a lot of other formulas without the use of a calculator. And I've never needed it since. Nowadays all your digital thermometers will read either and your cell phone has an app for it. Another cool app I found useful is the inclinometer app which allows you to get the pitch of a fan blade or the pitch of your deck surfaces.
25°C......................77°F
x 2 = 50................-32 = 45
- 1/10 = 45...........+ 1/10 = 50
+32 = 77°F...........x ½ = 25°C

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Challenge is to find an instant step conversion. C to F:
(found on internet - if I locate the source again, I'll post it here.)
F to C: Harder but doable.
Can't think in Centigrade, I'm a Fahrenheit fan.
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C to F: double C > minus 10% > plus 32 = F (accurate)
F to C: F minus 30 > plus 10% > take half = C (close enough)

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F is literate.
C is laboratory: at zero water freezes, at 100° water boils.

F zero, it's too frikking cold even in Denmark.
At two digit 32° it's freezing, but you got a chance.
At F 100°, it's getting into a 3-alarm heat wave
(while in C scale, it'll be 37.5° - close to freezing in my book.)

Fahrenheit is a finer tuned scale and more expressive.
98.6° is normal human body temp. 104° it's heat stroke or fever,
a 5.4° spread. For emphasis, it crosses a two to a three digit gradient.
Celsius, it's 37° and 40° - a 3° separation. Fahrenheit says it way better.

Holy catfish! it's going to be over 37.5° today! ....no, rilly?.....