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Weekly Problem 47 - 2011

Challenge Level: Challenge Level:1

Equal regular pentagons are placed together to form a ring as shown in the diagram, which shows the first three pentagons.

How many more pentagons are needed to complete the ring?

circle with chain of 3 pentagons.

 

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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