【How-to】What is a 3x3 magic square

This is a unique magic square because not only do the rows, columns, and diagonals add up to the same number, but the four corners, the four middle squares (17, 9, 24, 89), the first and last rows two numbers in middle (12, 18, 86, 23), and the first and last columns two middle numbers (88, 10, 25, 16) all add up to …