Reversible Magic Squares
Reversible magic squares are magic squares where when each number is rotated 180 degrees,
they keep being a magic square and keep the same magic constant. This can
only be achieved using numbers 1,6,8,9 because when these are flipped they
will still be a number (6 flipped is 9, 8 flipped is 8). However, when
the numbers are displayed with the 7 segment display representation (as can be seen in the image on the left), a reversible magic square can also exist with
the numbers 2 and 5.