IKMC 2013 - Grades 5-6 - Self-study Question 27

When Matthew and Marten found their old model railway, Matthew quickly made a perfect circle from 8 identical track parts. Marten starts to make another track with two of these pieces as shown in the picture. He wants to use as few pieces as possible to make a closed track. How many pieces does his track consist of?



Standard track convention: the track is a simple closed loop, without crossings or overlapping track pieces.