Post #1620638

68°F. If you think of 20°C as super conveniently being room temperature (68°F) and use that as an anchor; you can then, within about +/- 40°F, think of every +/-5°C as about +/-10°F. For example: * 20 - 10 = 10°C (50°C) is approx. 68 - 20 = 48°F * 20 - 20 = 0°C (32°F) is approx. 68 - 40 = 28°C * 20 + 10 = 30°C (86°F) is approx. 68 + 20 = 88°F That is, if you use 20°C/68°F as an anchor, take the difference in Celsius from 20°C, multiply that by two, and add it to 68°F, you have a decent approximation of what the temperature is in Fahrenheit. That's assuming 20°C is the only anchor you have and that you never want to learn what other temps are – just a compact, minimal-memorization algorithm that gets you close enough for the rare times you need it. (The real algorithm is that `x°C = (y°F - 32) ÷ (1.8)`)