title: simplest way to echo one value of one row
body: <p>I have this simple query </p>
  
  <pre><code>$qry = "select MAX(image_id) from tpf_images";
  $res = $pdo-&gt;query($qry);
  </code></pre>
  
  <p>the result of which is just one number. What is the quickest, simplest way to echo that number out with php?</p>
  
  <p>Thanks</p>