> This is just a formatting/display issue. Excel isn't rounding the number internally.
It isn't rounding or truncating while you are actively using the workbook or saving in its native formats, but it does when saving back out to CSV or certain other formats.
As much as I like Excel for many things, it is sometimes the bane of my existence wrt people using it to manipulate tabular data that isn't in its native formats and causing accidental corruption.
One of the many projects on my list of “things I'll never get around to” is a good⃰ CSV (or other text-based tabular data) editor.
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[*] There are actually quite a few that look good, but don't have some of the features behaviours I want, or in some cases are not available on an appropriate platform (there are a couple of Mac only options for instance), or are paid proprietary apps that are surprisingly expensive (I could justify it and get work to pay in DayJob, but not for my own use).
In 2020, scientists decided just to rework the alphanumeric symbols they used to represent genes rather than try to deal with an Excel feature that was interpreting their names as dates and (un)helpfully reformatting them automatically. Yesterday, a member of the Excel team posted that the company is rolling out an update on Windows and macOS to fix that.
It sounds like the problem in this case is that you don't know how to use basic Excel features.