Matrices
Ok, i'm guessing your talking about sticking it into a calculator(which is the easiest way in my opinion but the long way is not that bad either.)
I have a Silver TI 84 but the TI 83 works the same way.
You go to 2nd inverse (x^-1) which says matrix on the top.
It should have names, math, and edit.
Go to edit to plug in your given matrices.
It should say Matrix A 1_x_1 you can adjust it according to the size of your matrix.
You plug in the first # and press enter. Go on until you have all your #'s inserted.
then press 2nd MODE
you should be back on the main screen. Go back to 2nd inverse where you got to matrix and go to mathe to find the determinix. If you have another matrix add it in, under edit. To multipyly to matrices go to the names and press [A] then go back to names and press .
I hope this helped!