# Term for numbers that have at least one non-zero significant digit after the decimal point?

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?

• Real numbers. Are you looking for a term describing some subset of the reals? Like non-integer reals? "Decimal" and "floating point" have certain connotations in computing. Floating point means the potentially imprecise representation of a real, while decimal implies the precise representation of a base-10 real number... – stevesliva Jan 13 '15 at 4:29
• @stevesliva: I've modified the question; "real" is of course correct, but not particularly useful to describe numbers to most people that aren't e.g. professional mathematicians/programmers. Maybe tags are still wrong, though. – Nathan Tuggy Jan 13 '15 at 4:33
• I would have thought it's just "decimals." Like you "learn decimals" in grade school, in that you discover what a decimal point is for. It also matches fairly well with the comp-sci definition of "decimal number." – stevesliva Jan 13 '15 at 4:35
• @stevesliva, I've not seen the adjective form of decimal, used in the narrow sense here, outside CS. (Even in CS, it's far more about numbers that are stored in a particular way than about numbers that definitely have a mantissa attached.) – Nathan Tuggy Jan 13 '15 at 4:38
• The word "mantissa" has multiple uses and with your new edit, I am do not know what meaning you are using. Three links: this seems to be close to how you are using the word mathworld.wolfram.com/Mantissa.html; or as a synonym of en.wikipedia.org/wiki/Significand; or as the fractional portion of the common log en.wikipedia.org/wiki/Mantissa. Which definition are you using? Maybe use bold or italics to highlight the exact digits you want a name for. – hunterhogan Jan 13 '15 at 5:35

## 3 Answers

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.

• This is peculiar, because it does not sound familiar to me. "Mixed decimal", though, I could understand fairly well. Maybe that will do the job. E: Or more citations/quoted usages would help I guess. – Nathan Tuggy Jan 13 '15 at 5:43
• Outside math and computer science, it's just "decimal number." In common usage, that signifies having a decimal point, not being base 10. And the "number" is implicit in "decimals" the same way it is in "fractions." – stevesliva Jan 13 '15 at 5:46
• Hmm, looks like one of the related questions in the sidebar uses decimal in this sense. OK, can't really argue with that. – Nathan Tuggy Jan 13 '15 at 6:47
• "Decimals" as a noun is perhaps less common as non-integer numbers of all varieties become more ubiquitous and more precise terms gain more traction. But it would most definitely have been the answer 30 years ago. – stevesliva Jan 13 '15 at 6:50

A noninteger.

Cf. integer at dictionary.com.

Ugly word, though, considering 'in-' itself stands for 'non-'.

• It might be edifying to continue this etymology rant to its conclusion. :) If in- means non-, and teger means touchable, integers are untouchable and non integers mean not untouchable. :) – SrJoven Jan 13 '15 at 18:29
• Nonintegral might also work for the adjective form, yeah. – Nathan Tuggy Jan 13 '15 at 21:06

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.

1. 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.
2. Spurious digit(s)
3. Extraneous digit(s)
4. Imprecise digit(s)
5. Falsely precise value
6. Non-normalized digit(s)/value
7. 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."

• Edited question to clarify a bit more; I'm not so concerned with false precision as with numbers that happen to have any precision beyond the integral at all, and, colloquially, "need" that precision. – Nathan Tuggy Jan 13 '15 at 5:26