Yes, there is a much simpler way, and it’s a shame they don’t teach it in school. Once those complicated formulas with all their parentheses and 32s got into a textbook somewhere, they seem to have taken on a life of their own.
Here’s the simple method: To convert a Celsius temperature to Fahrenheit, just add 40, multiply by 1.8, and subtract 40.
That’s all there is to it.
For example, to convert 100 degrees Celsius, we’ll add 40 to get 140, multiply by 1.8 to get 252, and then subtract 40 to get 212. What do you know! That’s the boiling temperature of water: 100 degrees Celsius equals 212 degrees Fahrenheit. The great thing about this method is that it works in both directions, to wit: To convert a Fahrenheit temperature to Celsius, just add 40, divide by 1.8, and subtract 40.
Example: to convert 32 degrees Fahrenheit to Celsius, we’ll add 40 to get 72, divide by 1.8 to get 40, then subtract 40 to get, and there you are!, 0. That’s the freezing temperature of water: 32 degrees Fahrenheit equals 0 degrees Celsius.
All you have to remember is whether to multiply or divide by 1.8. Hint: Fahrenheit temperatures are always bigger numbers than Celsius. So when you’re going toward Fahrenheit, you multiply.
Why does this method work? Because of the ways that Messrs. Fahrenheit and Celsius set up their temperature scales. It turns out accidentally that 40 degrees below zero on either scale represents exactly the same temperature.
So adding 40 puts them on the same basis, so to speak. Then all we have to do is correct for the different sizes of the degrees (a Celsius degree is exactly 1.8 times as big as a Fahrenheit degree), and finally we remove the artificial 40 that we added.
A more detailed proof of why this method works would constitute a smaller nit than we care to pick at the moment. But it always works, and it is exact.
