Choose an integer number between 1 and 99 (let's take for example 67). Subtract from this number each of the two digits that make it.
(in our example, the result is : 67 - 6 - 7 = 54)
Look at the table bellow : each symbol correspond to a number. Find the symbol corresponding to yours and repeat it in your mind for 5 seconds.
Finally, click on the magic square !