On a digital clock showing 24 hour time, over a whole day, how many
times does a 5 appear? Is it the same number for a 12 hour clock
over a whole day?
Stuart's watch loses two minutes every hour. Adam's watch gains one
minute every hour. Use the information to work out what time (the
real time) they arrived at the airport.
Where can you draw a line on a clock face so that the numbers on
both sides have the same total?
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
Bernard Bagnall recommends some primary school problems which use
numbers from the environment around us, from clocks to house
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?
Is it possible to rearrange the numbers 1,2......12 around a clock
face in such a way that every two numbers in adjacent positions
differ by any of 3, 4 or 5 hours?
During the third hour after midnight the hands on a clock point in
the same direction (so one hand is over the top of the other). At
what time, to the nearest second, does this happen?
Use your knowledge of angles to work out how many degrees the hour
and minute hands of a clock travel through in different amounts of
These clocks have only one hand, but can you work out what time
they are showing from the information?
These two challenges will test your time-keeping!
Can you put these mixed-up times in order? You could arrange them in a circle.
How many times in twelve hours do the hands of a clock form a right
angle? Use the interactivity to check your answers.
Which segment on a digital clock is lit most each day? Which
segment is lit least? Does it make any difference if it is set to
12 hours or 24 hours?
Sometime during every hour the minute hand lies directly above the hour hand. At what time between 4 and 5 o'clock does this happen?
On a clock the three hands - the second, minute and hour hands - are on the same axis. How often in a 24 hour day will the second hand be parallel to either of the two other hands?
These clocks have been reflected in a mirror. What times do they
This investigation explores using different shapes as the hands of
the clock. What things occur as the the hands move.