Every so often, I come across the phrase "a million and a half X" - which always strikes me as strange: it suggests 1000000.5 of the thing. I was taught to use instead "one and a half million" to be unambiguous.

Is the first form actually acceptable, though? Or is it just sloppy writing/editing?


Context is really important. If you want to go down that road of possible ambiguity, then "one and a half million" could also be interpreted as 1 + 500,000, right?

In reality, the context will be such that nobody will be confused no matter which of the two you use. How often does the number 1,000,000.5 come up? Extremely rarely. 1.5 million, on the other hand, comes up all the time. In conversation, I think you'll hear both of these phrasings used for 1.5 million with very little confusion, because everyone will assume you mean 1.5 million. So, in that sense, both can be considered acceptable. (Compare this to saying "fifteen thousand hundred", which you'd have a hard time calling "acceptable".)

However, in a publication of some kind, it is probably seen as better, clearer writing to use "one and a half million". In this kind of one-way communication, you only have one chance to get your message across, so you should make sure it is understood. If I were told by my editor to only write "one and a half million", I would consider that a reasonable edit.

  • I wish I could have taken you to exactly 10,000, however childish that might be. At least I was the one to push you over it. Congratulations. Oh and it feels good to have the power to pull you back again too, though I must share this power with many others. – Cerberus_Reinstate_Monica Jan 6 '11 at 2:56
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    @Cerberus: Actually, I did have exactly 10,000 earlier tonight but then voted down someone's answer! :) – Kosmonaut Jan 6 '11 at 4:29
  • @Kosmonaut: Hah, what, was this masochism or sadism? – Cerberus_Reinstate_Monica Jan 6 '11 at 4:30
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    If there is any chance of someone interpreting "one and a half million" to be 1,000,000.5, using hyphens will help ("One-and-a-half million"). – Tragicomic Jan 6 '11 at 8:55
  • Here's a boost from 10.1 to 10.1. (^_^) – RegDwigнt Jan 6 '11 at 11:14

Interestingly, "a million and a half" and "a billion and a half" sound normal to my ear, with the meaning being 1.5 of each, but "a hundred and a half" and "a thousand and a half" don't. I'm not sure why this is.

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    probably because “a half a hundred” and “a half a thousand” are not quantities that people typically speak of. They’d say “fifty” or “five hundred”. – nohat Jan 5 '11 at 18:13
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    And fifteen hundred, now that I think of it. – Robusto Jan 5 '11 at 18:54

It is certainly acceptable and I would not consider it sloppy writing, at all. While one-and-a-half million is correct, it sounds awkward and I daresay it is less commonly used. In regular conversation, one would probably hear one-point-five million, instead. With the indefinite article, the half usually comes after the million: a million and a half.

There are several examples of the -and-a-half construction, in which half consistently refers to the preceding unit:

  • an hour and a half
  • a month and a half
  • a dozen and a half
  • one year and a half
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    I would use any of them with 'one' (or 'a(n)'), but to me "two days and a half" sounds stilted. – Colin Fine Jan 5 '11 at 17:05
  • @Colin Fine: I will admit that example sounded odd to me, too, but it seemed grammatically, when I created it. I don't think I have ever used such a construction, so I'll take it out. Thanks! – Jimi Oke Jan 5 '11 at 18:26
  • The difference is that with the time units, "X and a half" doesn't sound as odd because they are indeed perceived as a single unit - not as 60 minutes, or 30 days, or whatever. Whereas with "a million" (or "a dozen," for that matter) you perceive the discrete units, and then appending "a half" to those could be ambiguous. – Alex Jan 5 '11 at 23:38
  • In norwegian we have a strange expression for 1.5 that translates to something like "half-second", which basically means "half way to the second from the first". This has always stumbled me, as when I have thought about it, it sounds like "half of two" which is 1, but technically it is "half of the second", which indicates that you already have the one, and you want just half of the second in addition. – awe Jan 6 '11 at 10:20
  • I would regard the noun phrase "a million and a half" as meaning "a million and a half [million]", but I would disfavor using such phrasing as a count adjective. – supercat May 1 '14 at 13:37

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