C#.NET - Calculation sum in DataTable

DataTable dtSum = new DataTable();

        dtSum.Columns.Add("Name");

        dtSum.Columns.Add("Salary");

        for (int i = 1; i < 5; i++)

        {

            DataRow drRow = dtSum.NewRow();

            drRow["Name"] = i.ToString();

            drRow["Salary"] = (1 * 100).ToString();

            dtSum.Rows.Add(drRow);

        }

        decimal dAccuracy = Convert.ToDecimal(dtSum.Compute("Sum(Salary)", "").ToString());