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Have you ever given someone a problem which they can't solve after hours, when you can produce an answer in a matter of minutes? If not, here's your chance!
A magic square is a N x N array of cells, each cell containing one of the first N2 positive integers, such that the sum of the numbers along any row, column and the two diagonals is a constant. De la Loubere was the French Ambassador to Thailand in 1687-1688 when he learnt the following method for odd values of N.
Write 1 in the middle cell of the top row. Now keep writing 2,3,4,... in the up-right direction. If you reach the end of the square, `come out' on its opposite side. If you have to write on a used square, go down one cell. For example, here is a 7 by 7 magic square.
30 39 48 1 10 19 28 38 47 7 9 18 27 29 46 6 8 17 26 35 37 5 14 16 25 34 36 45 13 15 24 33 42 44 4 21 23 32 41 43 3 12 22 31 40 49 2 11 20
This method gives only 1 magic square for any N. There are many others. Methods of creating even magic squares are known, but are not this elegant.
Now, go and ask your best friend to create a 99 by 99 magic square...