Puzzle #28: A well-timed nap
2 November 2019
Posted by on
From New Scientist #3254, 2nd November 2019 [link] [link]
I keep an analogue clock by my bed. One afternoon, I had a nap. When I drifted off to sleep, the minute hand was pointing directly at one of the 12 numbers on the clock face, and the number of minutes past the hour was exactly the same as the angle (in degrees) between the hour and minute hands.
Later that day, when I woke up, I noticed the same was true again.
How long had I been asleep?