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This rather strange diagram is called the Enneagram. It has an obscure history and is quite widely used in psychological and spiritual work. But it's also interesting from a mathematical point of view. Here's how it can be generated:
Draw the circle, and write the numbers from 9 down to 1 around the edge in an anticlockwise direction, starting at the top.
Work out the decimal version of the fraction 1/7, which is 0.142857142857142857...
Draw lines between the digits in that decimal: 1 to 4 to 2 to 8 to 5 to 7 and back to 1.
Do the same for the fraction 41/111: that's 0.369369369. Or equivalently, just draw lines between the remaining numbers.
I wonder if the person who first came up with the Enneagram figure generated it in this way, or whether the connection to the decimal form of 1/7 is just a coincidence. We will never know, because the Enneagram first came into recorded history via an unusual character called George Gurdjieff, who was well known for telling fibs and encouraged his followers to drink lots of vodka. Vodka and maths are both very enjoyable in their own way, but they do not go very well together in my experience.
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