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Reading "0.22" as "o point two two" should make "an" correct. Reading "0.22" as "zero point two two" should make "a" correct.

Can the author decide? Are both correct or is only one of them correct?

Before posting this, I checked When should I use "a" vs "an"? and Google - but googling that proved difficult.

marked as duplicate by curiousdannii, BladorthinTheGrey, tchrist Dec 28 '16 at 10:37

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

  • I suspect has been answered in some form on this site. Hopefully someone can find it or answer. Of course, you can avoid the problem by just omitting the zero ".22" :) – GetzelR Dec 27 '16 at 17:29
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    I would suggest that you use "a". If the reader wants to read the digit zero as "oh", that's his problem. – Mick Dec 27 '16 at 17:38
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    What your question really is, is whether the zero in 0.22 is read aloud as "oh" or "zero" (or possibly "naught"). The answer to that question would then drive whether you use "a" or "an. The pronunciation of "0" is addressed in this ELU question. I don't know if the answers and comments there will satisfy your question, but it's worth a look. – Katherine Lockwood Dec 28 '16 at 0:05

Use "a". Most of the time when referring to a quantity of zero point anything, the zero isn't mentioned. In english all of the zeroes to the left of the non zero digits (and decimal point) can safely be ignored. Which means the proper way to say that is "a point twenty-two* μm filter".

*"a point two two μm filter" would also be acceptable.

  • See english.stackexchange.com/a/62398 for reasons why saying point twenty-two is potentially problematic. In summary, that answer says: if in next breath you say point two, that could then be confusing- 0.02 vs 0.2. – k1eran Dec 27 '16 at 21:24
  • I disagree with the linked answer. Admittedly context is important, as mentioned... but if it's chapters/rules there's generally not a part zero. In fact generally the first rule/chapter/section will be 1.1 (or maybe 1.1.1 etc). If I say point twenty-two and then point two, the second number I said is point oh two less than the first, not point two less. – aslum Dec 27 '16 at 21:35

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