Magic circle (mathematics)

For other uses, see Magic circle (disambiguation).
Yang Hui's magic concentric circles – numbers on each circle and diameter (ignoring the middle 9) sum to 138

Magic circles were invented by the Song dynasty (960–1279) Chinese mathematician Yang Hui (c. 1238–1298). It is the arrangement of natural numbers on circles where the sum of the numbers on each circle and the sum of numbers on diameters are identical. One of his magic circles was constructed from the natural numbers from 1 to 33 arranged on four concentric circles, with 9 at the center.