How many squares are in a 20 x 13 array?

In a 20 x 13 array, you can count the total number of squares by considering all possible square sizes. The number of k x k squares in an m x n rectangle is given by (m - k + 1)(n - k + 1). For a 20 x 13 array, you can have squares of sizes ranging from 1x1 to 13x13 (the smaller dimension). Summing the squares for each size yields a total of 1,710 squares.