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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?
Crossing the Atlantic
Every day at noon a boat leaves Le Havre for New York while another boat leaves New York for Le Havre. The ocean crossing takes seven days. How many boats will each boat cross during their journey?
Age 11 to 14
Challenge Level
A digital clock shows hours and minutes as illustrated below.
 |
for example 9:38pm is displayed as |
Which segment 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?
NRICH is part of the family of activities in the Millennium Mathematics Project.