If you think about the formula for converting, it’s close to multiplying or dividing by 2. This step is off by about 10% (1.8/2=0.9). So converting from F to C, subtract 32, divide by 2, then add 10%.
For C to F, multiply by 2, subtract 10%, then add 32.
At typical temps, I’ve found this is usually within a degree, and easy to do in my head (and I have zero working memory).
The two formulas are:
F=(C x 1.8)+32
C=(F-32)/1.8
If you think about the formula for converting, it’s close to multiplying or dividing by 2. This step is off by about 10% (1.8/2=0.9). So converting from F to C, subtract 32, divide by 2, then add 10%.
For C to F, multiply by 2, subtract 10%, then add 32.
At typical temps, I’ve found this is usually within a degree, and easy to do in my head (and I have zero working memory).