### Speedy Sidney

Two trains set off at the same time from each end of a single straight railway line. A very fast bee starts off in front of the first train and flies continuously back and forth between the two trains. How far does Sidney fly before he is squashed between the two trains?

### Rule of Three

If it takes four men one day to build a wall, how long does it take 60,000 men to build a similar wall?

### Digital Times

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?

# Three of a Kind

##### Stage: 3 Short Challenge Level:
See all short problems arranged by curriculum topic in the short problems collection

The time shown on a digital clock is 5:55.

How many minutes will pass before the clock next shows a time for which all the digits are the same?

If you liked this problem, here is an NRICH task which challenges you to use similar mathematical ideas.

This problem is taken from the UKMT Mathematical Challenges.