$max = 10;
$gbox = 'green';
$ybox = 'yellow';
echo '<table><tbody>';
for ( $r = 0; $r <= $max; $r++ ) {
echo '<tr>';
for ( $c = 0; $c <= $max; $c++ ) {
$box_color = 'white';
$value = $c;
if ( $r == 0 ) {
$box_color = $gbox;
if ( $c == 0 ) {
$value = '';
}
} elseif ( $c == 0 ) {
$box_color = $gbox;
$value = $r;
} else {
$value = $r * $c;
if ( $c <= $r ) {
$box_color = $ybox;
}
}
echo '<td style="background-color: ' . $box_color . ';">';
echo $value;
echo '</td>';
}
echo '</tr>';
}
echo '</tbody></table>';