The conversion from °F to °C is more complex: subtract 32 and then multiply by 5/9 (or 0.555555555).
That's cumbersome for mental math.
Here's a shortcut: subtract 30 and divide by 2 OR multiply by 2 and add 30.
- How good is that shortcut?
- Are there temperatures that it's okay for and other temperatures that the shortcut is too far off?
- Is this just another stupid shortcut? NixTheTricks ?