Set a digital clock to display in 24-hour (military) time. Each day, it will show you 211 prime numbers starting with 00:02 (2 minutes after midnight) and ending with 23:57 (3 minutes before the next midnight.)

Oh, and 211 is also prime, so 02:11 would be one of the 211 prime times you observe each day.

I'm a Professor of Mathematics and a University Distinguished Teaching Professor at the University of North Texas. For eight years, I was co-director of Teach North Texas, UNT's program for preparing secondary teachers of mathematics and science.
View all posts by John Quintanilla