Most of the Rest Of the World
Most of the rest of the world uses Celsius to tell temperature, uses the 24-hour system to tell time. It’s understandable that converting to such a “foreign” scale or system can be daunting. Plus, why relearn something for which you might already have an intuitive sense, like with the Fahrenheit scale, for us here in America?
Outside of my studies (more useful and more common in everyday life), I have tried to develop a sense for these “foreign” things. I started off with the 24-hour system about 5 years ago. Now, it’s second-nature. I have since moved on to getting a feel for the Celsius temperature scale.
The obvious thing to do would probably be to memorize a few formulas for the conversion of what you know to what you want to know (i.e. number of miles to number of kilometers). The same applies to the all-too-familiar equation of Fahrenheit to Celsius, and vice versa. Here’s what I’ve discovered (note: some math may be required).
C to F Conversion
F to C Conversion
1. 24-Hours
We all know that the 24-hour clock is nothing more than a means to get rid of the AM/PM suffix at the end of our times. It is a cleaner way to represent time and it completely avoids ambiguity (maybe except for 00:00 and 24:00, which represent the same time). Say the time is 21:47. To convert that craziness to something we know, what would we do? Of course we would take 21:47 and subtract 12:00. Depending on how proficient you are at finding the difference of times, you’ll quickly arrive at 9:47 pm (the pm comes from the fact that it is past 12:00 noon).
Someone once told me that rather than doing the subtraction, or going through the motions of doing mental math, simply take the “21″ and decrement it by 2 (which comes from subtracting the “12″). Two less than 21 is 19 which “rounds down” to 9.
You can argue that it is the same as subtracting. Well, it is, to be sure. But this decrementing by two is far easier for me than pretending I can do subtraction in my head. So, 18:07 is just 6:07 pm.
2. Celsius Temperature Scale
Recently, I was toying around with the Weather widget on my iPhone. I converted it to Celsius and I wanted to see how long it would take for me to get frustrated and switch it back to degrees F. Well, in the practical range of moderate temperature, we can simply approximate the temperature formula. 9/5 becomes about 2, and 32 is about 30. The formula goes from [9/5*C + 32] to [2*C + 30], which is far easier to work with, I’d say.
Let’s assume the temperature is 20 degrees C. Doing some thinking, we take 20, multiply it by 2, and add 30. It is about 70 degrees F. (If we use the proper formula we get 68 degrees F.) Close enough!
Be careful though. This approximating becomes terribly useless as you get further from the “linear range” of -10 to +30 degrees C. Most of the time, it wouldn’t matter if you’re just considering the weather, but the approximation deviates more and more from actuality. For small degrees C, it would underapproximate, and for larger degrees C, it would overapproximate. Just keep that in mind.
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