...
        <tr>
         <td class="order2" width="266"><p>Transaction Number:</p>
      </td>
         <td class="order3" width="324">V64F66697601</td>
      </tr>
...

##</code><code>##

...
my $order_reg = "<p>Transaction Number:<\/p>\n.*<\/td>\n.*<td .*>(.*)<\/td>";

if ($request->content =~ /$order_reg/s) {
  print "\nmatched $1\n";
}