[hnick]

Your assertion sounded incorrect so I tested it. Quoting large numbers does not preserve them on a save.

Adding a ' before it should work, but for data extracted from arbitrary systems you'll have few guarantees of the sort. Formatting the cells in Excel to display the full value instead of the truncated value also works from memory, but you won't always know ahead of time if this happened later in the file.

In our case it was often mailing identifier barcodes so any loss of precision made them entirely useless.