Which times on a digital clock have a line of symmetry? Which look
the same upside-down? You might like to try this investigation and
This investigation explores using different shapes as the hands of
the clock. What things occur as the the hands move.
Do you know the rhyme about ten green bottles hanging on a wall? If
the first bottle fell at ten past five and the others fell down at
5 minute intervals, what time would the last bottle fall down?
Beatrix has a $24$-hour digital clock on a glass table-top next to her desk. When she looked at the clock at $13$:$08$ she noticed that the reflected display also read $13$:$08$.
This problem is taken from the UKMT Mathematical Challenges.