Protection and security in Excel
If you have a table with sensitive information (credit card numbers, numbers personal phone numbers, insurance policies) to third parties you can customize the display only the last digits of the number.
If the sheet is not frequently used, it is possible to hide it does not interfere with the display of tabs of the other sheets. If necessary it can be displayed via the menu item. Sheet you can hide "more", so it can be displayed only from editor VBE.
to avoid user temptation to change the formula, it is possible to hide them.