Format in Excel 2007
How to protect spreadsheets
You can significantly reduce the number of errors in data entry in Excel by protecting changes of specific
spreadsheets (worksheets) and cells.
Allow specific users to edit ranges in a protected spreadsheet
Excel offers you an ability to assign user-level permissions to different areas on a protected spreadsheet.
You can specify which users can edit a particular range while the spreadsheet is protected. As an option,
you can require a password to make changes.
Combining text and formatted values
The Excel TEXT function enables you to specify numbers and date format.