Brain Game: The Day the Brains Came

I'm old enough to remember a time before digital clocks, but I imagine before I'm dead that the art of reading an old-fashioned clock face won't even be taught in school. (At least I hope I live that long.) But while we're discussing digital clock readouts, here's today's Brain Game:

Over a 24-hour day, how many times would a digital clock with an hour/minute readout show a series of consecutive [ascending] digits (like 1:23)?

Click here for the answer.

Answer: Ten times. (These occur at 1:23, 2:34, 3:45, 4:56, and 12:34, both AM and PM.)