Ford Fairlane
Moderator
- Feb 21, 2002
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- Moderator
- #551
Seriously, I use a faster method:
°F - °C
30 - 0
40 - 5
50 - 10
60 - 15
70 - 20
80 - 25
90 - 30
Far from perfect, but it works.
The old double it and add 30 trick. Worked for us kids in primary school when working out if we would get swimming lessons.