Stage: 3 Challenge Level: 
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?
How many solutions can you find?
Can you convince us that you have all of them?
Working systematically. Cubes. Interactivities. Addition & subtraction. Combinations. Clock. Creating expressions/formulae. Mathematical reasoning & proof. Visualising. Generalising.
Published November 2003,December 2003.
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