Fills down from the top cell or cells in the specified range to the bottom of the range. The contents and formatting of the cell or cells in the top row are copied into the rest of the rows in the range.
expression.FillDown
expression Required. An expression that returns a Range object.
This example fills the range A1:A10 on the active worksheet, based on the contents of cell A1.
Spreadsheet1.ActiveSheet.Range("A1:A10").FillDown