Converting between degrees Celsius and degrees Fahrenheit isn't difficult. Remembering when to multiply by 5/9 or 9/5 and whether you have to add 32 or subtract 32 makes it fairly easy. Sometimes, though, fairly easy isn't easy enough. Students have trouble remembering the order of operations: "Do I add or subtract 32, and is that before or after I multiply?" Of course, knowing that 32[degrees] Fahrenheit is 0[degree] Celsius helps with remembering, but students don't always see it that way. And why is it that you subtract first when going from [degrees]F to [degrees]C, but multiply first when going the other way?