Approximately 5000 years ago, the Chinese Emperor Yu saw a divine tortoise in the Yang-tse river. Yu noticed strange and bizarre, yet mystical spots on the tortoise's shell.
This is what Yu saw.
Can you see what is peculiar about the pattern of spots?
Do you know what such patterns are called?
It turns out that the spots form a magic square (as shown).
Do you notice the sum of the numbers in every row and every column and each diagonal is the same.
Send us some of your own making.
Can you find a general rule for constructing magic squares?
For more details see the book Mathematical Recreations and Essays by Rouse Ball.
Read the Emperor Yu's story at: http://mathforum.org/alejandre/magic.square/loshu2.html