 Figure 1: Normal magic square. Image courtesy Sam Ley, St Louis, Missouri. 

A magic square is a square
matrix containing numbers
such that the sum of any row, column, or diagonal is the
same^{[1][2]}. A magic square using the
sequential numbers 1..n where n is the number of cells is called a
normal magic square. Magic squares are believed to
have been discovered in China about 4^{th} century BCE. The 3x3 normal
magic square was called 'Lo Shu' by the Chinese. Magic squares were known in
ancient Egypt, India, and Arabia.
