Here's how to convert between Celsius and Fahrenheit:

* Celsius to Fahrenheit: Multiply the Celsius temperature by 9/5, then add 32.

* Fahrenheit to Celsius: Subtract 32 from the Fahrenheit temperature, then multiply by 5/9.

Let's try converting 40 degrees Celsius to Fahrenheit:

* (40 * 9/5) + 32 = 104 degrees Fahrenheit

So, 40 degrees Celsius is equal to 104 degrees Fahrenheit.