<head>
<script language="javascript">
function addColumn()
{
var rows = document.all("mytable").rows;
for (var i=0; i < rows.length; i++)
{
var cells = rows[i].cells;
var sum = 0.0;
for (var j=0; j < cells.length; j++)
{
var txt = cells[j].innerText;
if (!isNaN(txt))
sum += parseFloat(txt);
}