I’ve always thought of it as the fraction 9/5 instead of 1.8. I think that makes it easier because you can break it down into two steps, dividing by 5 and multiplying by 9. can’t multiply by 9 in your head? well that’s easy, just multiply by 10 and subtract the original number. and dividing by 5 is just dividing by 10 and then doubling it.
(I really wish math education put more emphasis on breaking down problems into a series of smaller problems like this)
If you just need an estimate this is pretty easy to do in your head:
Degrees Celsius x2 +32 =Fahrenheit
(Degrees Fahrenheit -32 )/2 = Celsius
The real number is 1.8 but that’s a bit harder for most people to do without a calculator.
I’ve always thought of it as the fraction 9/5 instead of 1.8. I think that makes it easier because you can break it down into two steps, dividing by 5 and multiplying by 9. can’t multiply by 9 in your head? well that’s easy, just multiply by 10 and subtract the original number. and dividing by 5 is just dividing by 10 and then doubling it.
(I really wish math education put more emphasis on breaking down problems into a series of smaller problems like this)
Doesn’t “common core” kind of do that but parents complain?
To get closer add/subtract 30 instead of 32 so the formula is easier.
For my perfect example:
50F - 32 = 18 / 1.8 = 10C50F - 30 = 20 / 2 = 10C