I think you missed what they found weird. The subject for that was that 0.0491 only has three significant digits. It is not obvious why, if you don't normalize the number.
IOW, the final significant figure has continuously variable significance (but discretely intervalled numerically) depending on the absolute value of what is it supposed to be significant to.
This is a feature of granularity.
And rounding error has a variable influence on the intervals and how "discreet" or blatant any error may appear.
Then you've got error propagation and pretty soon you're going to need something like Gustafson's UNUM's:
This is almost completely wrong: the number of significant digits is something given by metadata, you cannot look at a number and know that it has been properly rounded to the correct number of significant digits. You always need to be told this special circumstance because most numbers you encounter have in fact not been properly rounded.
.000300 you have 3 significant figures.
300000 you could have 1 to 6 significant figures.
3.00x10^5 has three significant figures.There is the odd case of trailing zeroes in non decimal numbers, but otherwise if a number is written, when is that not assumed to be significant?
That is, there are fairly standard rules for conveying significant digits, I thought?
For example, the number you are viewing could have been produced with finite precision floating point math and then just rounded to an arbitrary chosen (small) number of digits.