When importing and manipulating data in Excel, certain coding systems (like CAS numbers) are always a problem because numbers like 8000-01-7 can become 7th of january 8000.
There is usually (but not always) a way to get around this, e.g. formatting all columns as text for a data import, pre-formatting all columns as text before pasting information to them etc.
However, there are a multitude of ways in which Excel's date conversation can creep in unexpectedly. When this happens, and going back to the source data is not possible, is there a way to get excel to return the original value? Or once it has been "helpfully" converted to a date is the original string information now lost?