$re = '/\$10(?=[^0-9])/';
$str = '$6
$7
You have received the grade of $3 in the subject $1 ($10) in the semester $2 ($11).
Grade date: $4
';
preg_match($re, $str, $matches, PREG_OFFSET_CAPTURE, 0);
// Print the entire match result
var_dump($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