Magic Squares
A magic square is a large square made up of n² smaller squares usually containing numbers 1 to n² such that the totals of all the rows, columns and the two diagonals are the same.
A magic square can re be rotated clockwise or anti-clockwise 90°, 180° or 270° and yet would retain its property. The second, third and fourth images are given to explain this point.
In ancient times such squares were thought to have magic properties, perhaps connected with the stars. Magic squares have been found in such widely divergent cultures as ancient China, Egypt, and India, as well as W Europe.
Magic squares have fascinated humanity throughout the ages, and have been around for over 4,000 years. They are found in a number of cultures, including Egypt and India, engraved on stone or metal and worn as talismans, the belief being that magic squares had astrological and divinatory qualities, their usage ensuring longevity and prevention of diseases.
Magic squares were known to Arab mathematicians, possibly as early as the 7th century, when the Arabs got into contact with Indian or South Asian culture, and learned Indian mathematics and astronomy, including other aspects of combinatorial mathematics. It has also been suggested that the idea came via China. The first magic squares of order 5 and 6 appear in an encyclopedia from Baghdad circa 983 AD, the Rasa'il Ihkwan al-Safa (the Encyclopedia of the Brethern of Purity); simpler magic squares were known to several earlier Arab mathematicians.
The Arab mathematician Al-Buni, who worked on magic squares around 1200 A.D., attributed mystical properties to them, although no details of these supposed properties are known. There are also references to the use of magic squares in astrological calculations, a practice that seems to have originated with the Arabs.
Certain extra restrictions can be imposed on magic squares. If not only the main diagonals but also the broken diagonals sum to the magic constant, the result is a panmagic square. If raising each number to certain powers yields another magic square, the result is a bimagic, a trimagic, or, in general, a multimagic square.
The side total or diagonal total of a magic square containing numbers from 1 to n² is given by the formula
However, magic squares can also be constructed using numbers 1+a to n²+a as given in the fifth magic square below which uses numbers from 2 to 10. In these cases, the side total or diagonal total of the magic square would be
The simplest magic square is that of the order 3 x 3. This is because a magic square containing the number 1 with no other squares cannot be said to be a magic square. The next option, a magic square of the order 2x2 does not exist because, for a magic square, the side total should be equal for different combinations of numbers. For any consecutive four numbers a,b,c, and d, only a+d=b+c and there are no other equalities whatever combination is tried.
Magic square 6 gives a magic square entirely comprising of prime numbers.
Rudolf Ondrejka (1928−2001) discovered the following 3x3 magic square of primes, in this case nine Chen primes:
Pictures 2 and 3 give you higher order magic squares such as 4x4, 5x5, and 6x6.