# Talk:Fahrenheit

I removed the following:

Fahrenheit 451, the title of a famous science-fiction novel by Ray Bradbury, refers to the temperature at which book paper supposedly burns. (Bradbury is said obtained this figure simply by calling a local fire station on the telephone).{{fact}}. The novel concerns a dystopian future in which imaginative fiction is considered subversives, and the job of "firemen" is to locate and burn books.

It doesn't belong on this page, but on Farenheit 451, which is where I moved it :) Jazzman831 14:47, 29 July 2007 (EDT)

## Removal of untrue statement

"To convert a temperature in Fahrenheit to Celsius, subtract 32 and multiply the result by 5/9.

The temperature -40 is the same in both scales. This gives an alternative conversion rule: to convert in either direction, first add 40; then multiply by 5/9 for °F->°C or 9/5 for °C->°F; then subtract 40."

The first paragraph quoted and the first sentence of the second paragraph quoted are true. The second sentence of the second paragraph is not.

Consider conversion of 100 degrees Fahrenheit into Celsius.

Using the first calculation:

(100-32) * (5/9) = 37.8 degrees Celsius

Using the second calculation:

(100+40) * (5/9) = 77.8 degrees Celsius

Body temperature is approx 100 degrees Fahrenheit and approx 38 degrees Celsius. I will remove the untrue part.

Barclay 16:15, 2 February 2011 (EST)

• Incorrect. Let's start with the first rule: "To convert a temperature in Fahrenheit to Celsius, subtract 32 and multiply the result by 5/9." So if we start with a temperature of °F:
(°F - 32) * (5 / 9)
°F * (5 / 9) - 32 * (5 / 9)
°F * (5 / 9) - (32 * 5) / 9
°F * (5 / 9) - (160 / 9)
With the second rule: "first add 40; then multiply by 5/9 for °F->°C or 9/5 for °C->°F; then subtract 40."
°F + 40
(°F + 40) * (5 / 9)
((°F + 40) * (5 / 9)) - 40
°F * (5 / 9) + 40 * (5 / 9) - 40
°F * (5 / 9) + 40 * (5 / 9) - 40 * (9 / 9)
°F * (5 / 9) - 40 * (4 / 9)
°F * (5 / 9) - (40 * 4) / 9
°F * (5 / 9) - (160 / 9)
They're mathematically equivalent.
Or just plug it in:
Using the first calculation and 212 °F (because it's exactly 100 °C):
(212 - 32) * (5 / 9) = 100 °C
Using the second calculation:
((212 + 40) * (5 / 9)) - 40 = 100 °C
Looks like you forgot to subtract 40 in the second conversion. I've replaced the second formula. DouglasL 13:20, 3 February 2011 (EST)