Today, I heard the first cry of cicadas. It's summer! And It is very hot. The maximum temperature is 30 deg. Celsius. But how do you say it in Fahrenheit?
I am sometimes confused with the two scales of temperature: Fahrenheit and Celsius.
You know Fahrenheit is used in a few countries including the U.S. I don't know why Fahrenheit is still commonly used in the U.S. even though many other countries use Celsius. Every time I talk about weather with them, I have to "translate" Celsius to Fahrenheit, and vice versa.
But it is ridiculous to always hold a pen and notes (or a calculator) to use this formula: (F=C*9/5+32). So I have several steps to easily calculate scales in my head.
Celsius to Fahrenheit:
You have a value C in Celsius.
1. Double C
C * 2
2. Subtract 10% of it
2C - 0.1 * 2C
3. Add 32
2C - 0.1 * 2C + 32
Then you get an exact value in Fahrenheit.
It is easier than expected.
For example, let's say the temperature is 30 deg. C.
So you can calculate as the below:
30*2=60
60-6=54
54+32=86 The temperature is exactly 86 deg. F.
In case of 20 deg. C.:
20*2=40
40-4=36
36+32=68 The temperature is 68 deg. F.
The reason can be derived from the formula.
F=C*9/5+32
=C*2/2*9/5+32
=C*2*(9/10)+32
=C*2*0.9+32
=C*2-C*2*0.1+32
Fahrenheit to Celsius:
You have a value F in Fahrenheit.
1. Divide F by 2
F/2
2. Subtract 16 from it
F/2 - 16
3. Add 10% of it
F/2-16 + 0.1 * (F/2-16)
In this case, you get an approximately value in Celsius.
For example, let's say the temperature is 70 deg. F.
So you can calculate as the below:
70/2=35
35-16=19
19+1.9=20.9 The temperature is about 21 deg. C.
The reason can be derived from the formula.
C=(F-32)*5/9
=(F-32)/2*2*5/9
=(F/2-16)*10/9
=(F/2-16)*1.11111...
≒(F/2-16)*1.1
7/09/2012
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