A square array of numbers, usually positive integers, is called a magic square if the sums of the numbers in each row, each column, and both main diagonals are the same. The summation of the first row gives 42, hence the summation of each row, coloumn and diagonals should be 42. 13+12+17=42 13+E+11=42 E+13+11=42 E+24=42 E=42−24 E=18