Format a 170 x 170 cell area in Excel 2013 with a gray background and a black border.

ExcelLifeBookFormatting.cs

private void ApplyFormatting(int rows, int columns)
{
    // Complete surrounding borders of the gray box. 
    Range[Cells[1, 1], Cells[rows, columns]].Interior.Color = Color.LightGray;
    Range[Cells[1, 1], Cells[rows, columns]].Borders[XlBordersIndex.xlEdgeTop].LineStyle = XlLineStyle.xlContinuous;
    Range[Cells[1, 1], Cells[rows, columns]].Borders[XlBordersIndex.xlEdgeLeft].LineStyle = XlLineStyle.xlContinuous;
    Range[Cells[1, 1], Cells[rows, columns]].Borders[XlBordersIndex.xlEdgeBottom].LineStyle = XlLineStyle.xlContinuous;
    Range[Cells[1, 1], Cells[rows, columns]].Borders[XlBordersIndex.xlEdgeRight].LineStyle = XlLineStyle.xlContinuous;

    // Set all column width to 2.14. That's a nice looking width.
    for (var i = 1; i <= 170; i++)
    {
        var column = Columns[i, System.Type.Missing] as Range;
        if (column != null) column.EntireColumn.ColumnWidth = 2.14;
    }
}