$re = '/\d(?:[ \/]+\d){0,4}/m';
$str = '1 2 3 4 5
123/45
1234 5
1 234 4
1/234/5
1/234 5
1 2/3 4/5
1 2345
1 ////23/////45';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php