skript na vypočet nefunguje

<script type="javascript">
function pocitaj(){
   var virtual = document.getElementById('virtual').value;
   var real = virtual/10000;
   document.getElementById('real').innerHTML = real;
}
</script>
<form action="exchange.php" method="post">
  <table>
    <tr>
      <td>Virtual money</td>
      <td><input type="text" name="virtual" id="virtual" value="" onkeypress="pocitaj()"></td>
    </tr>
    <tr>
      <td>Real money</td>
      <td><input type="text" name="real" id="real" value="" readonly="readonly"></td>
    </tr>
  </table>
</form>

function pocitaj(){
   var virtual = document.getElementById('virtual').value;
   var real = virtual/10000;
   document.getElementById('real').value = real;
}