A large square is sub-divided into equal number of rows and columns. Numbers are filled into the resulting
array of smaller boxes in such a way that, usually, the total
of numbers in any row or in any column or in any diagonal is the same.
In 4 by 4 squares, in addition, even the total of the four corner numbers will be the same!
These are known as Magic Squares
Magic squares have 3 by 3, 4 by 4, 5 by 5, ...
These have 32
, ... smaller boxes.
So magic squares may have 9, 16, 25, 36, 49, ..., smaller boxes and
these will need that many numbers to fill.
Note that square of an odd number is odd; of an even number is even
While he was in school, young Ramanujan
was fond of magic-squares; he created magic squares and played with them.