Here's a quick tip for temperatures.
C to F: Multiply the temperature by 2 and then add 30
(actual formula is multiply by 1.8, add 32)
ex: 22 C is roughly equal to 74 degrees using this method, actual conversion is 71.6
F to C: Now just work it backwards, subtract 30 from the temp. and then divide by 2
(again, actual formula constants are 1.8 and 32)
