try this.. :)
DataTable dtGetadata=GetDataTable();
public DataTable GetDataTable ()
{
DataTable dtData=new DataTable();
int Total=0;
for(int i=0;i<10;i++)
{
Total+=Convert.ToInt32(dtData.Rows[i]["amount"]);
}
dtData.Rows.Add("","Total",Total);
return dtData;
}