The Fahrenheit and Celsius scales have the same numerical reading at -40 degrees.

Here's why:

* Fahrenheit to Celsius conversion:

°C = (°F - 32) × 5/9

* Celsius to Fahrenheit conversion:

°F = (°C × 9/5) + 32

If you plug in -40 for either °F or °C in the appropriate formula, you'll get -40 for the other temperature.