Just drove up from Florida to New York, and what I did to keep occupied (apart from driving) was work out what fraction of the journey had gone. eg, 100 miles = 1/12, 200 miles = 16, 450 miles = 3/8.
I would enter my starting and ending destination, and use GPS to determing exactly what fraction
of the juurney is left, taking into consideration any detours I make

She: Well, finally. Here we are! Just look at that canyon! what an amazing sight!
He: Um, honey...something's wrong. The fractometer only reads 19/20. I think we must've missed part of the trip.
She: What're you talking about? The Grand Canyon is right in front of us!
He: <shifting the car into reverse> It must've been that detour we had to take at Flagstaff. We've got to go back and complete the trip.
She: Let me out of this car right now!

I first misread this as having something to do with fractals - so the closer you look at the dial, the more accurately it tells you how far you have travelled (ie. kilometres, metres, centimetres, millimetres, micrometres, nanometres ad infinitum).