multiple vars not working in Javascript
<p>I'm trying to take a height given in feet and inches and convert it to inches (eg. 6'1" would be 73"). When I only have one select box (the feet box) I can successfully convert it to inches. But when I add the 'inches' variable and try to add it to the converted 'feet' variable nothing happens. </p>

<p>Here's the script:</p>

<pre><code>&lt;script type="text/javascript" language="javascript"&gt;

function Calculate() {

    var feet = document.getElementById("feet").value;
    var inches = document.getElementbyId("inches").value;

    height = ((feet*12) + inches);

    document.write ('This is your height in inches:&lt;b&gt;   ' + height.toFixed(0) + '&lt;/b&gt;&lt;br&gt;');
}


&lt;/script&gt;
</code></pre>

<p>And the HTML:</p>

<pre><code>&lt;div class="form"&gt;
Height:
&lt;select id="feet"&gt;
  &lt;option value="4"&gt;4&lt;/option&gt;
  &lt;option value="5"&gt;5&lt;/option&gt;
  &lt;option value="6"&gt;6&lt;/option&gt;
  &lt;option value="7"&gt;7&lt;/option&gt;
&lt;/select&gt;

&lt;select id="inches"&gt;
  &lt;option value="0"&gt;0&lt;/option&gt;
  &lt;option value="1"&gt;1&lt;/option&gt;
  &lt;option value="2"&gt;2&lt;/option&gt;
  &lt;option value="3"&gt;3&lt;/option&gt;
  &lt;option value="4"&gt;4&lt;/option&gt;
  &lt;option value="5"&gt;5&lt;/option&gt;
  &lt;option value="6"&gt;6&lt;/option&gt;
  &lt;option value="7"&gt;7&lt;/option&gt;
  &lt;option value="8"&gt;8&lt;/option&gt;
  &lt;option value="9"&gt;9&lt;/option&gt;
  &lt;option value="10"&gt;10&lt;/option&gt;
  &lt;option value="11"&gt;11&lt;/option&gt;
&lt;/select&gt;
&lt;br /&gt;
&lt;input type="submit" value="Calculate" onclick="Calculate()" /&gt;
</code></pre>

<p></p>

<p>Thanks in advance</p>
