12 x 12 = 9
23 x 23 = 16
25 x 25 = ?
13
12 x 12 = 144 => 1 + 4 + 4 = 9
13 x 13 = 169 => 1 + 6 + 9 = 16
25 x 25 = 625 => 6 + 2 + 5 = 13
13
12 x 12 = 144 => 1 + 4 + 4 = 9
13 x 13 = 169 => 1 + 6 + 9 = 16
25 x 25 = 625 => 6 + 2 + 5 = 13