//--- Open a workbook.
          ExcelApplication xla = new ExcelApplication();
          Workbook wb = xla.Open(@"C:\report.xls");

          //--- Create a style.
          Style percentStyle = wb.CreateStyle();

          //--- Specify that the number format for the style is a percentage with three
          //--- decimal places (0.000%).
          //--- The following line is equivalent to percentStyle.NumberFormat = "0.000%"
          percentStyle.NumberFormat = wb.NumberFormat.CreatePercentage(3);
        

          '--- Open a workbook.
          Dim xla As New ExcelApplication()
          Dim wb As Workbook = xla.Open("C:\report.xls")

          '--- Create a style.
          Dim percentStyle As Style = wb.CreateStyle()

          '--- Specify that the number format for the style is a percentage with three
          '--- decimal places (0.000%).
          '--- The following line is equivalent to percentStyle.NumberFormat = "0.000%"
          percentStyle.NumberFormat = wb.NumberFormat.CreatePercentage(3)