Animated Counter / Clock in Blender

I have searched and searched for a method to creating a counter/clock 
for one of my animations.  Does anybody know of a good tutorial that 
explains how to "animate" the text to change according to the timeline 
in an animation?

The project I am working on is to simulate pallet movements on an 
assembly line and I would like to show a clock and counter to 
demonstrate how long pallets are sitting in a station.