Often data that looks numeric to the user is actually stored as text in Excel, meaning Excel formulae's don't work on it. This can happen if copying and pasting data directly from an Access database, or out of a Chemistry Output Table that ESdat has produced.
This function allows you to select the range you wish to clean, you can select the entire spreadsheet, and it will clean all the used cells within the spreadsheet.
The function does not affect any non-blank or formulae cells, so it will not affect your data.