$re = '/(\w+\s+\d+,\d+\s+\d+,\d+\s+)\((\s+\d+\s+)\)(\s+)\((\s+\d+,\d+\s)\)(\s+\d+)/m';
$str = 'IBNR 13,123 1,234 ( 556 ) ( 2,355 ) 934 ';
$subst = "$1$2$3$4$5";
$result = preg_replace($re, $subst, $str);
echo "The result of the substitution is ".$result;
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