Should we use plural or singular for a fraction of a mile?

I have seen people say both 0.25 mile and 0.25 miles. Should we use plural or singular for a fraction of a mile?

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Is the question about what is correct to write, or what you should say? – kiamlaluno Aug 29 '10 at 23:18
In Irish, plurals are not used directly after a number. This has affected Hiberno-English, and "five mile" would not be an uncommon phrasing here. Elsewhere, @ShreevatsaR's answer applies. – TRiG Jan 25 '11 at 1:17
@TRiG: Make that an answer. – Mechanical snail Sep 12 '12 at 5:25

0.25 miles.

The rule I follow is that you use the singular only when talking of exactly one mile. You'd also say half a mile, quarter of a mile, etc., but in these cases it's as though you're still talking of "a mile" first, and then taking half or quarter of it.

Let me say something further, with the caveat that it may be my own idiosyncratic usage: use the singular only when talking of the natural number 1, that is, when you're essentially "counting" miles and there's a single one of them. Use the plural in all other cases, even for the real number 1.0: just like "0.9 miles" or "1.1 miles", also say "1.0 miles" (but "1 mile").

[Mathematically, natural numbers ("counting numbers") are a subset of real numbers, but more properly what we have is an inclusion map, so it does make sense to distinguish between 1 and 1.0, actually. And the distinction between natural numbers and real numbers does have applications elsewhere in English: consider "fewer than" versus "less than". You'd say "fewer than five items" but "less than 5.0 inches", since a length doesn't have to be an integer number of inches, you're not counting but assigning a real value.]

Another aside: the SI standard for symbols is to use the same symbol for singular or plural, so you'd write "2 km" even if you were reading it as "2 kilometres". Of course, since you're using miles, you probably don't care about this. :-)

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Your way of doing "1.0 miles" is how I would say it too. Cool observation. – Kosmonaut Sep 2 '10 at 15:44
If you choose to abbreviate Imperial units, you would also say 2 mi, 1 mi, 3.14159 mi, etc. – mskfisher Sep 2 '10 at 15:47
And of course, since zero is not the same as one, this means that a plural is always used when there are none - "0 miles", "no miles", "no avocados" and so on. – psmears Jan 21 '11 at 13:49
Actually this doesn't just have to do with natural numbers vs. real numbers -- it has more to do with the word "one". For example, "I have three minus two cars" uses the plural, despite the number of cars being the natural number one. (You can't argue that this has to be interpreted as short for "three cars minus two cars", because that expansion doesn't work for "three times two cars" or "six divided by two cars".) See extensive discussion in a related question about -1. – Matt Nov 24 '11 at 10:45

Depends how you say it. You'd say "nought point two five miles" (plural) but "a quarter of a mile" (singular)

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Well, some people would say "zero point two five", or "oh point two five", or just "point two five". Not too many noughts in the U.S. – mmyers Aug 29 '10 at 5:51
That's because when you're talking about "a quarter mile" you are essentially saying "1" unit measured in "quarter-miles". Your unit of measure is different. There's still one of them. – OneProton Sep 24 '10 at 15:20

I'd leave it singular unless talking about a range such as "0.25 - 2 miles". In a table, for example, the heading would be the same regardless of the units. You can always abbreviate as "mi" and avoid the issue.

Simon's answer is also good. Also note that it's actually more awkward to say 0.25 mile than "point two five of a mile".

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I don't think this is helpful, abbreviating or table headings aren't really relevant to the point. – delete Aug 29 '10 at 7:12
No context was given, so we really don't know what will or won't be helpful. – Neil Fein Aug 29 '10 at 20:58
true, there is not much context, but without context the most general case would apply, and thus abbreviations or table headings don't seem relevant. – delete Aug 30 '10 at 2:50
The same applies to "1 to 2 miles" so it isn't decimal specific – OneProton Sep 24 '10 at 15:27
"Point two five of a mile" seems a bit more awkward than "Point two five miles" – Little Big Bot Jun 6 '13 at 16:15

For reasons I'm not too sure about, we usually say "0.25 miles" rather than "0.25 mile". If you Google for both terms, there are about 700,000 "0.25 miles" but less than 100,000 "0.25 mile", and the first few hits for "0.25 mile" give things like "0.25 mile swim" or "0.25 mile wireless setup", where the "mile" is forced to singular anyway.

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If we followed the definition of "plural", the correct usage would be:

0.25 mile

0.5 mile

0.9 mile

1.0 mile

1.3 mile (or 1.3 miles, according to Wiktionary note below)

2.0 miles

2.2 miles ..

As the definition is:

Plural: of, relating to, or constituting a class of grammatical forms usually used to denote more than one or in some languages more than two

http://www.merriam-webster.com/dictionary/plural

However, as Shinto pointed out in his answer here, people usually use the plural form for 0.25.

Here is an interesting note from the Wiktionary about the usage of plural for fractions (and decimals) in general:

While the plural form generally refers to two or more persons or things, that is not always the case. The plural form is often used for zero persons or things, for fractional things in a quantity greater than one, and for people or things when the quantity is unknown.

This does support the usage of plural for 0.25 though, since it is less than one. But if that is how people use it, we definitely can't say that it is incorrect.

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really, though, in English plural is used for any number that is not 1. 1 mile, 1 1/4 miles, 1.3 miles, 1.00000001 miles, 0.9 miles, 0 miles, etc. – nohat Aug 29 '10 at 11:42
Even 1.00 miles isn't necessarily one mile; it could be anywhere from about 0.995 to 1.005, so I'd suggest the plural there too. – supercat May 1 '14 at 6:15

.25 miles or a quarter of a mile.

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It's really not complicated or confusing if you think of it in terms of being a fraction.

Essentially, as soon as you go into decimal, you're changing units into partial units.

0.25 would actually be 25 units of "hundredth-miles"

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protected by tchristJul 1 '14 at 1:01

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