The Magic Circle Puzzle
Magic circles are quite similar to magic squares. In the magic circle above, we have to place the numbers 1 through 9 in the interior of the red circles. If we add the numbers on any circle (blue or yellow) and the number at the center, the sum should be equal to the sum of each “diagonal” of the circle.
For a little trivia, magic circles are said to have been invented by Japanese mathematician Kittoku Isomura (c. 1660).