Range.NumberFormat (Excel)

Returns or sets a value that represents the format code for the object.

This property returns Null if all cells in the specified range don't have the same number format. The format code is the same string as the Format Codes option in the Format Cells dialog box. The Format function uses different format code strings than do the NumberFormat and NumberFormatLocal properties. For more information, see Number format codes (Microsoft Support).

Worksheets("Sheet1").Range("A17").NumberFormat = "General" 
Worksheets("Sheet1").Rows(1).NumberFormat = "hh:mm:ss" 
Worksheets("Sheet1").Columns("C"). _ 
 NumberFormat = "$#,##0.00_);[Red]($#,##0.00)"