I spent time studying for my FAA exam this morning by attending the flight school's ground school. Today's session was about multiple topics that will be on the exam, in the form of a Jeopardy game. I won't bore you with the nerdy details of what I learned.

EXCEPT for this really cool trick for converting Celsius to Fahrenheit in your head without fancy math or needing to know it's 9/5 plus 32. Ready?

Prime example: let's start with 15° C
First, double the number = 30
Take away 10% = 30-3= 27
Add 32 = 27+32= 59° F
That's it!

Another example:
9° C doubled = 18
18 take 10% = 16.2 (I'll round down)
16 add 32= 48
48° F

Last example:
38° C doubled= 76
76 take 10%= 68.4 (I'll round down)
68 add 32= 100
100° F

Let's go backwards!
59° F
subtract 32 = 27
add 10% = 27+2.7= 29.7 (I'll round up)
30 in half is 15° C

85° F minus 32=
53 add 10%= 58.3 (I'll round down)
58 in half is 29° C


This doesn't help me pass my exam or fly any better, but now I can convert inflight or without my E6B handy if I need to.

(Thanks Captain!)