So, a number that is nothing but fractions is "fractional". A number that has a whole number and a fraction is "mixed", if you want to call it that. And the portion after the decimal point is called the mantissa in at least some (all?) contexts, although many would not know this word. But how about numbers that have a whole part and a non-zero mantissa, such as 1.93 or 159.2 or -0.8, as opposed to 5 or 5.00? What do you call those in more or less conversational English?
As I mentioned in the comments, I truly think Decimal is the word you're looking for.
It is used in everyday language to mean precisely what you want it to.
Furthermore, if you have a separate category of "integers" or "whole numbers," it would be absolutely clear what a "decimal" category would mean.
Cf. integer at dictionary.com.
Ugly word, though, considering 'in-' itself stands for 'non-'.
I doubt there is a specific word for those digits in the same way that "remainder" has a mathematical meaning when performing integer division.
Nevertheless, some words can well describe the digits to which you refer. The Wikipedia article on Significant figures implies many options.
- Overestimated value (in most cases) because a significant figure is a floor function, additional non-zero digits after the significant digits increase the value of the number from its "precise" value.
- Spurious digit(s)
- Extraneous digit(s)
- Imprecise digit(s)
- Falsely precise value
- Non-normalized digit(s)/value
- Non-confident (In-confident? Un-confident? Poopy-confident?) digit(s)
You should publish a paper in a journal about this problem, and then we can call the digits improperly appended to significant figures "Tuggy digits."