What Does This Button Do?

It didn’t take long to find something that completely threw me for a loop. A division symbol on a button sat right in the middle of the center stack. And right next to that was a subtraction sign.

Usually I like a trip computer to do my math for me. Wouldn’t adding up figures lead to distracted driving?

Granted, you’d learn what they’re used for a day or two after owning the Focus, but that doesn’t excuse the awful design.