The above \(3 \) by \(3\) square have letters A to I. Substitute these letters with numbers \(1\) through \(9\) without repeitition such that all their rows, columns, and diagonals adds up to the same value.
\(a\) denote as the value of the sum of each row, column, or diagonal,
\(b\) denote as the value of the middle number (i.e. E),
\(c\) denote the sum of the four corner numbers.
Picture Source File: 3 by 3 square