مساعدة في العمليات الحسابية +-*/ في أعمدة قواعد البيانات و العنصر DBGrid

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        private void DataGridView1_RowLeave(object sender, DataGridViewCellEventArgs e)
        {
            decimal nTotalDebit = 0;
            decimal nTotalCredit = 0;
            foreach (DataRow MoveDayDetailRow in this.dsMoveDayDetail.tMoveDayDetail.Rows)
            {
                try
                {
                      nTotalCredit = nTotalCredit + Convert.ToDecimal(MoveDayDetailRow["tnMoveDayDetailMoneyCredit"].ToString());
                      nTotalDebit = nTotalDebit + Convert.ToDecimal(MoveDayDetailRow["tnMoveDayDetailMoneyDebit"].ToString());
                }
                catch (Exception ex) { MessageBox.Show(ex.Message); }
                totalDebit.Text = nTotalDebit.ToString().Replace(".0000", ".00");
                totalCredit.Text = nTotalCredit.ToString().Replace(".0000", ".00");
            }
        }