Assembly: Microsoft.Office.Interop.Excel (in microsoft.office.interop.excel.dll)
If the cell contains a constant, this property returns the constant. If the cell is empty, the property returns an empty string. If the cell contains a formula, the property returns the formula as a string, in the same format in which it would be displayed in the formula bar (including the equal sign).
If you set the value or formula of a cell to a date, Microsoft Excel checks to see whether that cell is already formatted with one of the date or time number formats. If not, the number format is changed to the default short date number format.
If the range is a one- or two-dimensional range, you can set the formula to an array of the same dimensions. Similarly, you can put the formula into an array.
Setting the formula of a multiple-cell range fills all cells in the range with the formula.