Try it Both Ways

          for my $x (0..2) {
            for my $y (0..2) {
              $squares->[$x][$y] = $page->param("[$x][$y]");
            }
          }

          for my $n (0..8) {
            my ($x, $y) = (int($n/3), $n%3);
            $squares->[$x][$y] = $page->param("[$x][$y]");
          }

          for my $n (0..8) {
            $squares->[$n/3][$n%3] = 
              $page->param("[".int($n/3)."][".$n%3."]");
          }