Magic Square Puzzle Cube, 1976 1976 is the centennial of that book classification system known as the Dewey Decimal. Keeping with the number theme, the Humanitarians Not Heroes product this year is a 4 x 4 Magic Square Puzzle Cube . A "magic square" is a rectangular array of numbers in which each column, row, and both diagonals have the same sum. There are 880 different solutions to the 4 x 4 square. One of the six on this cube is extracted from the well known Albrecht Durer print Melancholy (1514), in which the same square can be seen in the upper right corner. The HNH Magic Square Puzzle Cube is a dizzying game of mathematics, and not for the faint of heart. In Durer's time, magic squares were considered charms against the plague. We think that's just charming. 
