Hello guys. This is my first question with mathOverflow so I hope my etiquette is up to par here.

My question is regarding a 3x3 magic square constructed using the la Loubere method (see la Loubere method)

Using the method, I have constructed a magic square and several semimagic squares (where one or both of the diagonals do not add up to a magic sum) with a program on written on my graphing calculator. After playing around with the program, I was shocked that the determinants of these 3x3 magic squares are all the same (specifically -360). Why is this so? (I am still an undergraduate so please go easy on the math :] )