Clock Arithmetic and Number Theory - November 2003, Stage 1&2

Problems

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Planet Plex Time

Stage: 1 Challenge Level: Challenge Level:1

On Planet Plex, there are only 6 hours in the day. Can you answer these questions about how Arog the Alien spends his day?

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Six in a Circle

Stage: 1 Challenge Level: Challenge Level:2 Challenge Level:2

If there is a ring of six chairs and thirty children must either sit on a chair or stand behind one, how many children will be behind each chair?

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Trebling

Stage: 2 Challenge Level: Challenge Level:1

Can you replace the letters with numbers? Is there only one solution in each case?

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The Deca Tree

Stage: 2 Challenge Level: Challenge Level:1

Find out what a Deca Tree is and then work out how many leaves there will be after the woodcutter has cut off a trunk, a branch, a twig and a leaf.

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A Square of Numbers

Stage: 2 Challenge Level: Challenge Level:1

Can you put the numbers 1 to 8 into the circles so that the four calculations are correct?

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Adding Plus

Stage: 2 Challenge Level: Challenge Level:2 Challenge Level:2

Can you put plus signs in so this is true? 1 2 3 4 5 6 7 8 9 = 99 How many ways can you do it?