well more than that is wrong since there is no way of getting 54 degrees in any event.
consider 54 deg 54 min 54 seconds
54 deg 54 +54/60 min
54 deg 54.90 min
54 deg 54.9/60
notice it never gets to 55, no matter how hard you try.
quit trying to use those old formula since they lead to errors, just use sequential math and you will notice that you don't 'add' to the degree portion it 'becomes' the decimal portion a conceptual versus mathematical difference