Which formula is used to convert Fahrenheit to Celsius?

• A. C = (F − 32) / 1.8
• B. C = F − 32
• C. C = 9/5 F + 32
• D. F = (C − 32) / 1.8

Answer: (A)

Converting Fahrenheit to Celsius involves removing the 32-degree offset between the scales and then adjusting for the difference in how big each degree is. The Fahrenheit degree is 1.8 times larger than a Celsius degree, so you divide by 1.8 (or multiply by 5/9) after subtracting 32. This gives C = (F − 32) / 1.8, which is the same as C = (F − 32) × 5/9. For example, 212°F → (212 − 32)/1.8 = 180/1.8 = 100°C. Subtracting 32 alone isn’t enough, because it ignores the different unit sizes. The form C = 9/5 F + 32 would convert Fahrenheit to Celsius incorrectly; that’s the reverse direction (Fahrenheit from Celsius). And F = (C − 32)/1.8 misplaces the operations.