THE FAHRENHEIT SCALE

In much of the English-speaking world, and especially in the United States, the Fahrenheit temperature scale (°F) is used by laypeople. A Fahrenheit degree is the same size as a Rankine degree. However, the scale is situated differently. The melting temperature of pure water ice at sea level is +32°F, and the boiling point of pure liquid water is +212°F. Thus, + 32°F corresponds to 0°C, and +212°F corresponds to +100°C. Absolute zero is approximately -459.67°F.
The most common temperature conversions you are likely to perform involve changing a Fahrenheit reading to Celsius, or vice versa. Formulas have been developed for this purpose. Let F be the temperature in °F, and let C be the temperature in °C. Then, if you need to convert from °F to °C, use this formula:
F = 1.8C +32
If you need to convert a reading from °C to °F, use this formula:
C = 5/9(F - 32)
While the constants in these equations are expressed only to one or two significant figures (1.8, 5/9, and 32), they can be considered mathematically exact for calculation purposes.
Figure 1 is a nomograph you can use for approximate temperature conversions in the range from -50°C to +150°C.
When you hear someone say that the temperature at the core of a star is 30 million °F, the Rankine reading is about the same, but the Celsius and Kelvin readings are only about 5/9 as great.

Fig. 1. This nomograph can be used for approximate conversions between temperatures in °F and °C.