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Place four pebbles on the sand in the form of a square. Keep adding as few pebbles as necessary to double the area. How many extra pebbles are added each time?

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Adding All Nine

Make a set of numbers that use all the digits from 1 to 9, once and once only. Add them up. The result is divisible by 9. Add each of the digits in the new number. What is their sum? Now try some other possibilities for yourself!

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For this challenge, you'll need to play Got It! Can you explain the strategy for winning this game with any target?

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Stage: 3 Short Challenge Level: Challenge Level:1

'Saturn' chocolate bars are packed either in boxes of 5 or boxes of 12.
What is the smallest number of full boxes required to pack exactly 2005 'Saturn' bars?

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.
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