A few things here:
If you put in symbols, spaces, commas, etc, Excel will see the entry as
text, and will faithfully reproduce the full text entry - not sure how many
characters you can have in a text string these days - a couple of thousand, I
think, but I'm not sure. But as text, you won't be able to do any numerical
calculations with it.
The behaviour you describe is not an error, it's just the way Excel is
programmed to work - numbers with 12 or more digits will be displayed in
scientific notation if the number format is "General". The point is of
course that in any real world application the measurement errors and
uncertainties in the data are such that only the first 2 or 3 or 4 digits are
meaningful, and that's what's displayed in scientific notation. If you think
the 11th, 12th and 13th digits are real, you're kidding yourself.
Re the truncation of the last digits, you did well to get 16 remaining - my
version only gives 15. Whatever, that's the internal calculation accuracy of
Excel, to 15 significant figures. That's why you'll sometimes find that
calculations that should yield zero actually result in values of the form
x.xxE-yy, where yy is 10 or more - i.e., very small non-zero values. But as
above, if you think anything more than the first few digits mean anything in
any real world application, you're kidding yourself, so 15 significant
figures is far more accurate than most people need. And Excel is geared to
the needs of most people, not a few technical specialists. So if you really
need more than 15 significant figures, Excel is not the tool for you, and
you'll also need to ensure that the processor chip in your computer can
actually handle your required level of precision - the applications you run
can't do better than your computer hardware!
Cheers
BrianH
