DataTable table1 = new DataTable("Registration");
table1.Columns.Add("L1");
table1.Columns.Add("L2");
table1.Columns.Add("L3");
table1.Rows.Add("1",5);
table1.Rows.Add("3", 5);
table1.Rows.Add("4", 9);
table1.Rows.Add("7", 3);
table1.Rows.Add("6", 6);
DataSet Dset = new DataSet("DSET1");
Dset.Tables.Add(table1);
if (Dset.Tables[0].Rows.Count > 0)
{
for (int i = 0; i < Dset.Tables[0].Rows.Count; i++)
{
DataRow dr = Dset.Tables[0].Rows[i];
int a = Convert.ToInt32(dr["L1"]);
int b = Convert.ToInt32(dr["L2"]);
int c = a * b;
dr["L3"] = c.ToString();
}
}
Good luck.