Try this,
find the two labels(i.e, quantity and price) from your gridview on row data bound and multiply two values and bind it in total column,
protected void GridView1_RowDataBound(object sender, GridViewRowEventArgs e)
{
if (e.Row.RowType == DataControlRowType.DataRow)
{
label lqty=(label)e.Row.findcontrol("Quantity_labelid_from Grid");
label lprice=(label)e.Row.findcontrol("Price_id_from Grid");
float total=float.parse(lqty.text)*float.parse(lprice.text);
label ltot=(label)e.Row.findcontrol("Total_columnId");
ltot.text=total.tostring();
}
}
[Edit member="Tadit"]
Added
pre
tags.
[/Edit]