To calculate the Fahrenheit temperature:
-- Take the Celsius temp.
-- Multiply by 1.8 .
-- Then add 32 to the product.
30°C ==> (30 x 1.8) = 54 ==> 54 + 32 = 86°F.
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To calculate the Celsius temperature:
-- Take the Fahrenheit temp.
-- Subtract 32 .
-- Multiply what's left by 0.55... (5/9 to be exact).
86°F ==> (86 - 32) = 54 ==> (54) x (5/9) = 30°C .