A turtle from a legendary river carried the first known magic square on its shell
Arrange the numbers 1 through 9 in a 3x3 grid so that every row, every column, and both diagonals add up to the exact same total. Chinese legend says the pattern first appeared on the shell of a turtle emerging from the Luo River around 650 BC.
Reveal the answer
One solution: 4-9-2 / 3-5-7 / 8-1-6, where every line sums to 15. Known as the Lo Shu ("Luo River Writing") square, it's the oldest magic square on record and, up to rotation and reflection, the only 3x3 arrangement that works. It became central to later Chinese divination and cosmology, and magic squares built on the same principle spread independently to India, the Middle East, and Europe over the following centuries.
— W. S. Andrews, Magic Squares and Cubes — Open Court Publishing, 1908 (documenting the Lo Shu legend)