How do I say “±” in English?

Question

I thought:

mathematical equation: 1 ± 1 - We can say "plus or minus one". Could I omit "or" to say "plus minus one"?
a signed mathematical number: ± 1 - We say "positive or negative one". Could I say "plus minus one" here?

Because "±1" only uses three syllables in Chinese, "positive or negative one" has 8 syllables which make it feel too long to me. "Plus minus one" is much shorter and more comfortable to me. I also know "positive/negative" stands for status, "plus/minus" stands for actions, if "positive or negative one" is the correct one, I would accept.

In terms of pronunciation, it's worth noting that in “plus or minus”, the “or” is very un-stressed, though still audible. In England, it'd just be /ə/, as in /ˌplʌ.sə.ˈmaɪ.nəs/. — mudri, Jul 27 '20 at 18:48
@James Wood You hint me the sound linking ! Yes, I usually forgot that, /ˌplʌ.sə.ˈmaɪ.nəs/ (with or ) almost has same sound length with /ˌplʌ.sˈmaɪ.nəs/ (without or) . Pronunciation difference is not significant , so the mainly problem is in writing -formal vs informal . — Mithril, Jul 28 '20 at 02:25
In some situations, especially in British English, "give or take one" may be used... but this tends to be slang/colloquial usage, so I'd avoid unless you know it "feels right" in context. — Dewi Morgan, Jul 28 '20 at 17:39
@mithril The 've' shouldn't take any noticeable time to pronounce--since 'posity' isn't a word, you don't need to emphasize the 've' to make a distinction. I think for most native speakers (certainly for me) in an unstressed context, you couldn't tell the difference between having the v at the end of 'positive' or at the beginning of 'or'. — Tiercelet, Jul 28 '20 at 18:19
@Tiercelet. Regarding that "positive or" could be heard as "posity vor": In Swedish a couple of words have taken a letter from a word they often followed; "upp å" (up on) has made "å" change to "på", and "-en I" (conjugation of verb + You) has made "I" become "Ni" (or usually "ni"). — md2perpe, Jul 29 '20 at 19:08
'Plus or minus' is completely correct and cannot be misunderstood. — Hollis Williams, Jul 29 '20 at 22:01
If something "feels too long" because you're used to a language that says the same thing in fewer syllables, just remember that when you're speaking English you're speaking English, not Chinese. And if you want to say something in Spanish it often will take even more syllables than saying the same thing in English. Still not an excuse to omit words. — David K, Jul 30 '20 at 02:24
As an aside: In german almost everyone says "plus-minus". a ± b is said "a plus-minus b", with plus-minus almost as a single word, while a + (-b) would be said as "a-plus minus-b* with a pause between plus and minus. This makes it fairly unambiguous. And when people speak english here, they simply do the same. — Polygnome, Jul 30 '20 at 11:16

Tyler M · Answer 1 · 2020-07-28T15:10:14.923

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I work as an engineer, and we talk about margins of error quite a bit. We all refer to it as plus minus one.

Seems the wikipedia article also calls it the plus-minus sign

Example:

Q: "Hey what's the length of this side?"

A: "The drawing says it's fifteen millimeters, plus minus point five." (15 ± 0.5mm)

Edit: For regional/dialect clarification, I was born, raised, and worked in central USA (state of Indiana)

edited Jul 28 '20 at 15:10

answered Jul 27 '20 at 20:09

Tyler M

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Yeah, I see how dropping the or would be a welcome convenience for communicating measured values. – brainchild Jul 27 '20 at 21:07
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I agree that "plus or minus" is the most complete, but I have to say that in contexts where the error bound is expected -- which is what we're talking about here -- I think I wouldn't be surprised by "plus minus". – Mike M Jul 27 '20 at 21:18
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The same is true in physics and, I assume, all other sciences where you care about measurement uncertainties. Nobody wants to say the "or" all the time, and everybody knows what you mean. – Graipher Jul 28 '20 at 05:38
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While just saying "plus-minus" is not uncommon, and won't lead to a misunderstanding, I'd say most native speakers of British English that I've come across in engineering and academia would at least hint at the existence of "or" in a very unstressed way - something like "plusser minus" – Chris H Jul 28 '20 at 10:55
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The name of the sign is a different matter from the way an expression is pronounced that contains the sign. The Wikipedia article on the sign gives no information about how to pronounce any of the expressions like the ones the mentioned in the question. – brainchild Jul 28 '20 at 11:06
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I don't think it's accurate to imply that Wikipedia only calls it a plus-minus sign. This is their actual text: "The plus–minus sign (also, plus or minus sign)..." – End Anti-Semitic Hate Jul 28 '20 at 11:26
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Just another anecdotal pebble on the pile, but I've never heard anyone say "plus minus". It always includes "or". Based on other responses, this may be a regional thing? – THE JOATMON Jul 28 '20 at 13:57
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Possibly a British usage, but I've only ever heard (and said) "plus or minus one". – Matthew Watson Jul 28 '20 at 14:12
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I agree with the previous two comments - as an American, I've only ever heard (and said) "plus or minus". The closest thing I've heard is something like "plus'r minus", which definitely isn't the same as dropping the "or" entirely. – probably_someone Jul 28 '20 at 14:38
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This kind of shortening that happens frequently in more specialized technical language. It's not common everyday usage among the general public, but it IS common in fields where this terminology is used very frequently, such as engineering, software development, etc. – barbecue Jul 28 '20 at 17:13
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Hmm, I have never, ever heard it said "plus minus". It is "plus or minus". – Fattie Jul 29 '20 at 12:28
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This answer is, simply, wrong I'm afraid. – Fattie Jul 29 '20 at 12:30
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Also there is no connection to Britishness. No one in Britain has ever said "plus minus". – Fattie Jul 29 '20 at 12:31
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@Fattie just because you've never heard it this way doesn't make it "simply wrong". I know plenty of professionals (some in academia, some in the workplace, some with 40+ years experience in their fields) who say "plus minus". Maybe you could argue "this isn't a British definition", and that's okay, but you having a narrow view doesn't make the answer "simply wrong." – Tyler M Jul 29 '20 at 13:03
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If just speaking to someone, you could go with 'give-or-take' – Rob Audenaerde Jul 29 '20 at 14:04
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The wikipedia article merely tells us the name of the unicode character, not how it is read in English. For example, "Bob & Marley" is not pronounced "Bob ampersand Marley", even though the name of & is "ampersand". – Cory Klein Jul 29 '20 at 15:42
In my career as a machinist I dealt with tolerances such as +/- 0.0005 almost daily. How do Chinese machinists express such tolerances in their day-to-day work? – user10637953 Jul 29 '20 at 17:43
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"wikipedia article also calls it the plus-minus sign" - plus-minus sign is just the official "name" given to that symbol in the Unicode database, it does not determine how it should be spoken in natural language. Just as / is SOLIDUS in Unicode, _ is LOW LINE and \`` isGRAVE ACCENT`. But more commonly known as slash, underscore and backtick respectively. @RockPaperLz-MaskitorCasket – MrWhite Jul 30 '20 at 00:29
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Ironically, as for me, Singaporean, I never ever heard it used as "plus or minus", other than the first time it was introduced in the quadratic equation. Everyone just uses "plus minus" here. – ministic2001 Jul 30 '20 at 02:01
@MrWhite Yes, very true. I sometimes wonder if I'm the only person who still calls ` a grave accent. – End Anti-Semitic Hate Jul 30 '20 at 05:46
I think this only covers the first use case in the question; not the second. – Jack Aidley Jul 30 '20 at 10:10

brainchild · Answer 2 · 2020-07-30T22:04:20.223

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Basic Answer

Generally, in English, you may pronounce the plus-minus sign (±) by saying "plus or minus".

Generally, you should not say "plus minus".

You do not need to know other details.

Detailed Answer

Specific Contexts

In some places, you may find that others say simply "plus minus". In other places, those who work with you may find it strange to hear this pronunciation. There is no universal rule. Generally, you should say "plus or minus", unless you discover that others in some place say "plus minus". Then, you might say either, as long as you remain in the same place.

American English

American English has a rule that British English does not have.

In American English, the way to pronounce a plus-minus sign depends on where the sign appears in a mathematical expression or numerical quantity.

If the sign appears between two terms in an expression, then the meaning is the plus operation (addition) or minus operation (subtraction). In this case, the pronunciation is the same as in British English, "plus or minus".
If the symbol appears before a confidence interval in the numeral part of a quantity, then too the pronunciation is "plus or minus".
If the symbol appears before the first term in an expression, then the meaning is that the term is positive or negative. In this case, the pronunciation is "positive or negative".

Canadians also follow the rule, as may those in other places that are affected more by American standards than by British. Schools in those countries teach this rule to children.

In practice, Americans and Canadians working in mathematics, science, and engineering often say "plus or minus", for convenience, the same as British, instead of "positive or negative". Some may choose, at certain times, to follow the rule for saying "positive or negative".

edited Jul 30 '20 at 22:04

answered Jul 27 '20 at 11:55

brainchild

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Thank you to those who explained the differences for AmE versus BrE. I integrated the information you gave me into the answer. – brainchild Jul 29 '20 at 06:22
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As an engineer and a native English speaker I'd beg to differ. You absolutely can just say "plus minus X". – ScottishTapWater Jul 29 '20 at 13:47
@Persistence Of which form of English are you a native speaker? – user81561 Jul 29 '20 at 14:28
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You have not sourced any of your claims, and "you should not say "plus minus"." does not align with how I was taught and is pretty ridiculous. – user117065 Jul 29 '20 at 16:19
@Greybeard English English... – ScottishTapWater Jul 29 '20 at 17:55
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You've made multiple claims about rules, that in my opinion as a BrE speaker are not applicable. As a scientist, I've always said (and heard other say) plus-minus in various different contexts. The "positive or negative" context only applies when discussing mathematical variables. – March Ho Jul 29 '20 at 18:47
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You make all kinds of statements about AmE and BrE and offer no proof at all. – Lambie Jul 29 '20 at 19:00
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I'm an American engineer and can back the "positive or negative" thing up. As epl said, in practice, "plus or minus" is sometimes used instead, but this is technically wrong. – Panzercrisis Jul 29 '20 at 21:05
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Folks, here's the thing. Someone has asked a question, who may be in an early stage of learning English, and has expressed a need for a comprehensible and agreeable way to pronounce a certain kind of math expression. This answer attempts to provide a simple and safe guideline, while also addressing the nuances rigorously. It is the only answer to this question that currently makes this attempt. – brainchild Jul 29 '20 at 21:51
Over time, this answer has received numerous helpful comments giving experiences from the US, UK, and elsewhere, many of those comments having received several dozen upvotes. I attempted to reflect the consensus of these comments and their votes in a revised response, while still preserving a simple and safe guideline. I then asked the moderator to delete the comments, as they were no longer necessary. I find this solution adequate, though not ideal, under the circumstances. – brainchild Jul 29 '20 at 21:52
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Ideally, the answer would cite sources, but so far, none have become available. I am happy to integrate any sources, or any other constructive feedback that anyone might offer. At the moment, we have a situation where the answer leading the vote count begins with, "I work as an engineer, and we...", while at the same time, various contributors have attached comments to this answer that take the form of, "I'm downvoting. This answer does not cite sources, and also, the claims are wrong, because they conflict with my opinion." We can do better. – brainchild Jul 29 '20 at 21:52
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"You do not need to know other details." assumes a heck of a lot about the situation of the asker. This answer would be better with out that statement. – JonathanZ Jul 30 '20 at 03:57
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What do you mean by "Ideally, the answer would cite sources, but so far, none have become available"? If you are going to find them and add citations, I believe it would be very useful to state this explicitly in your answer. If you would do it from the very beginning, I am convinced that this would avoid much of the unpleasant comment exchange above. – მამუკა ჯიბლაძე Jul 30 '20 at 19:01
@Persistence: I object to excluding "plus minus" as much as you. We only differ in that you think I have done so. The word can, or any derived from it, is by no accident omitted from the text of the answer. If you specifically identify which language from the text you find problematic, then your comments may be helpful. If you only offer your own interpretation, then I cannot change the text in any useful way, because I would not know how you have made that interpretation from the text. – brainchild Jul 30 '20 at 20:04
@MarchHo: As above, your thoughts may be useful, but only if you are specific about the language itself. If you only give me an interpretation of the text that is different from own, then I learn nothing. – brainchild Jul 30 '20 at 20:34

JonathanZ · Answer 3 · 2020-07-30T17:46:23.253

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People say it as "plus minus" all the time. (I'm a native speaker of AmEng, math guy). The other answers that say this is a bit informal and sometimes can lead to ambiguity are correct, but it is very common. If you're in a job interview you should include the "or", but if you're chatting with people "plus minus" is fine.

edited Jul 30 '20 at 17:46

answered Jul 28 '20 at 01:33

JonathanZ

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I agree. I don't know why people are getting so worked up about including the word "or" as if it were written into law somewhere. – sanitycheck Jul 30 '20 at 15:28

score 24 · Answer 4 · answered Jul 27 '20 at 11:04

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In English, I have never heard "plus minus one" used to refer to the ± symbol; it would be confused with:

x + -1

which could be spoken as "X plus minus one" and have a different meaning than x ± 1.

answered Jul 27 '20 at 11:04

rcook

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https://en.wikipedia.org/wiki/Plus%E2%80%93minus_sign and https://www.compart.com/en/unicode/U+00B1 both call the sign a "plus-minus sign", and I've often seen "plus-minus one" or "plus/minus one" being used. Although if there's potential for ambiguity, "plus or minus" is valid as well. – Maciej Stachowski Jul 27 '20 at 12:28
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@Maciej Stachowski Neither of those says plus minus one. They have an intervening punctuation mark, a dash or slash. – Bloke Down The Pub Jul 27 '20 at 20:22
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Macej: The sign is called the plus-minus sign, but we don't say the name of the sign when it appears in the expression. We just describe the meaning. – brainchild Jul 27 '20 at 21:34
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x+(-1) should be said as "x plus negative one". – Acccumulation Jul 28 '20 at 01:41
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I have heard it frequently. And the ambiguity you mention is avoided when speaking in two ways: 1) for the symbol in question the "plus minus" is said with almost no break between the two words, and 2) for the formula you show it would be said "exs plus negative one". – JonathanZ Jul 28 '20 at 04:57
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@BlokeDownThePub Do you pronounce a "carbon-neutral policy" as being a "carbon dash neutral policy"? No, you don't (or, at least, shouldn't). The punctuation mark can indicate the running-together of the two words, with not additional syllables; a shorter pause than "Plus Minus", but not quite "plusminus". – Chronocidal Jul 28 '20 at 13:45
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@Acccumulation In BrE (give or take a few regional dialects), it would more or less be "Plus minus-one", as opposed to "plus-minus one", – Chronocidal Jul 28 '20 at 13:47
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This was my first thought too. If I heard someone say "12 plus minus 1" I would think okay, 11... If I heard "12 plus or minus 1" I would think okay, 11-13. – THE JOATMON Jul 28 '20 at 14:01
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@MaciejStachowski Just because the unicode character is named "plus-minus" does not mean one should read it by its name in a sentence! – Cory Klein Jul 29 '20 at 15:39
Saying to add "minus 1" to something else isn't common IME with AmEng. It's always "negative 1". When speaking of the weather, do you say "negative ten" or "minus ten" when it's ten degrees below zero? AmEng is always "negative ten", "ten below", or "ten below zero", very rarely it's "minus ten" with the exception being the speaker misspeaking. – computercarguy Jul 29 '20 at 19:57

Void · Answer 5 · 2020-07-28T13:11:26.163

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mathematical equation : 1 ± 1 , we can say plus or minus one , could I omit or to say plus minus one?

a signed mathematical number: ± 1, we say positive or negtive one , but could I say plus minus one here?

No. If you omit the or, it will become ambiguous.
No.

Correct: plus or minus.

Incorrect: plus minus.

edited Jul 28 '20 at 13:11

answered Jul 27 '20 at 11:50

Void

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I disagree that "plus or minus" means "more or less". The phrase "more or less" is almost exclusively reserved for clauses like: "A is more or less B" (e.g. "the two courses are more or less identical"), in which case the meaning is closer to "A is approximately B". You would never say "the two courses are plus or minus identical". Instead, "plus or minus" is used in phrases like "the value of A is B plus or minus C" (e.g. "the value of pi is 3.14 plus or minus 0.01"), to specify the uncertainty on a particular quantity. You would never say "the value of pi is 3.14 more or less 0.01". – probably_someone Jul 27 '20 at 18:06
@probably_someone, My apologies. You're right. Thanks for explaining! I've edited my answer. – Void Jul 27 '20 at 18:13
@probably_someone: Make it a compromise: "more or less" means "± [some small amount]" instead of "±" by itself. – Flater Jul 27 '20 at 22:02
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In common non-technical usage, it's certainly true that phrases like "he was forty, plus or minus" have come into popular use to mean "he was about forty", and can also be expressed as "He was forty, more or less". I think this question is addressing more technical/formal usages, however. – Michael Kay Jul 27 '20 at 23:43
@MichaelKay I have literally never heard anyone say, "He was forty, plus or minus." – probably_someone Jul 28 '20 at 01:16
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@probably_someone have you heard anyone say "He was forty, give or take". That's a variation on the same theme – Chris Schaller Jul 28 '20 at 01:31
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@ChrisSchaller Yes, I have heard that phrase. That doesn't change the fact that I have literally never heard anyone say, "He was forty, plus or minus." – probably_someone Jul 28 '20 at 03:38
That's ok, @probably_someone what we can agree on then is that the meaning is the same, in different environments different colloquial phrases that have the same meaning become common place, but each would be understood if used in the other environment. – Chris Schaller Jul 28 '20 at 03:45
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@ChrisSchaller In what specific environment is the sentence, "He was forty, plus or minus." actually used? Can you point me to an example of native English speakers consistently using that sentence? There are lots of things that could technically have a particular meaning, but are never actually used in practice by native English speakers. Learning which phrases are idiomatic and which are not is particularly important for fluency, and incorrectly suggesting that "plus or minus" is idiomatic in the same situations as "more or less" or "give or take" is misleading. – probably_someone Jul 28 '20 at 03:53
@ChrisSchaller For example, many ESL speakers whose first language is Italian will use the phrase "take a decision" rather than "make a decision". The former is the literal translation of the Italian phrase "prendere una decisione", and while there's nothing that's actually grammatically incorrect about that construction, and it conveys the same meaning, it's simply not something that you would hear from a native English speaker. It's not idiomatic in English, and fluency requires that the ESL speaker recognize that "make a decision" is the appropriate phrase. – probably_someone Jul 28 '20 at 04:02
@probably_someone I often encounter new colloquial phrases that seem to be in popular use in some community, but previously unknown to me. That's the way language works. This is a typical example of a phrase (like "exponential growth") that has a precise technical meaning but spills out from the scientific community to people who use it more casually. There is of course an implied ellipsis: "plus or minus ...." suggesting that the speaker has stopped in mid-flow when he realises he doesn't have a numerical value for the standard error in the estimate. – Michael Kay Jul 28 '20 at 09:07
The downvotes have been explained. Your answer is nonsense, from an idiomatic perspective. The statements used are perfectly correct insofar as they are actually used and everyone involved understands what they mean. – Jul 28 '20 at 10:30
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For me, as a Br. Eng. speaker, this is the correct answer. – Greenonline Jul 28 '20 at 13:09
@MichaelKay You seem to be implying (but strangely, you never explicitly say) that you have encountered this sentence in common usage in some community. If this is true, then you should be able to find some documented usage of this sentence on the internet, correct? So let's see it. Identify the community, and show me evidence that people in that community use this sentence. The sentence "He was forty, plus or minus." is so gratingly non-idiomatic that I'm not just going to take your word for it that you've seen it in common usage. – probably_someone Jul 28 '20 at 13:12
@probably_someone You're not being fair about this - ", plus or minus" is perfectly natural usage in British English, but is only natural when spoken, so rather difficult to provide written evidence! – MikeB Jul 28 '20 at 17:19
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@MikeBrockington If it is, then there should be some recorded speech (i.e. audio or video) that will show it, correct? I've never heard this from the British English speakers I talk to, either. – probably_someone Jul 28 '20 at 17:20
@probably_someone actually, "take a decision" is fairly common among native speakers of British English. It's especially common with regard to official decisions by leaders. Interesting article: https://www.quickanddirtytips.com/education/grammar/take-decision-make-decision – barbecue Jul 28 '20 at 17:26
@barbecue The article and the referenced data do not make the distinction between usage among native speakers of English (British or otherwise) and usage among ESL speakers. Given that the data demonstrates that the phrase is already very uncommon, it's certainly possible that the data is actually tracking the number of ESL speakers who are mistakenly using this non-idiomatic phrase. – probably_someone Jul 28 '20 at 17:33
@probably_someone The article was not intended to be a comprehensive research study, just an interesting observation. However if you believe only ESL speakers use this phrase, you're wrong. It's commonly used by native English speakers. Jeremy Corbyn is not an ESL speaker, and he has used this wording. It's easy to find many more examples. – barbecue Jul 28 '20 at 17:51
@barbecue Can you show me specifically where Jeremy Corbyn has used this? – probably_someone Jul 28 '20 at 17:59

user81561 · Answer 6 · 2021-07-21T10:31:54.837

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The Google Ngram for plus or minus,plus-minus,plus and minus,plus minus is interesting You will see that “plus or minus” dominates the written use frequency.

Edit 20210721, 10:20GMT

Objections have been raised that this does not represent spoken English.

I have conceded this point in the first line. However, although the correlation between spoken and written English is not 1, it is close to 1 - we tend to write for our audience at the same level as we speak to our audience.
As symbols only appear in a written form, questions about how a symbol is spoken must therefore rely on the written form.
In speech, we learn, adopt, and then use words and phrases from written English.
Although corpuses of spoken English are good, they can never be 100% accurate: they describe only that minute percentage of speech that has been reliably reported.

edited Jul 21 '21 at 10:31

answered Jul 29 '20 at 14:36

user81561

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Finally, someone with evidence beyond anecdote. Someone buy this answerer a beer! – Cory Klein Jul 29 '20 at 15:40
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As good as this graph is for evidence, the Q is about how to say/speak it, not how people write it. I'd think that most of the things written are technical papers where correct grammar is a high priority (and where this data likely is gathered from), where speaking it's less important, especially in an informal or relaxed group, such as friends or co-workers. – computercarguy Jul 29 '20 at 20:02
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Although this graph takes the terms out of context. "plus or minus" and "plus minus" are both valid terms in written English, but they have different meaning. The fact that "plus or minus" is used more in written text doesn't necessarily mean it is any more correct in the context of this question. – MrWhite Jul 29 '20 at 23:29
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The premise of the question is that mathematical relationships are written using symbols that are distinct from any natural language, that give no indication of how they might be pronounced in any langauge, and that may be pronounced very differently depending on the context in which they occur and the population in which the are spoken. A written source informs this question only if it specifically explains a relationship between some symbol and some sequence of words. Otherwise, we may as well attempt to decipher hieroglyphics with no Rosetta Stone. – brainchild Jul 30 '20 at 08:36
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How does this answer the question, at all? the question isn't about what the proper written, expanded form of the symbol is, the question is about how to read it out aloud. Ngram doesn't answer this, at all. – Polygnome Jul 30 '20 at 11:12
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My vote: I very seldom hear "plus minus", almost always hear "plus or minus" and personally always say "plus or minus". BS Physics, MIT. I live in New England, USA. – Paul Chernoch Jul 30 '20 at 17:40

score 5 · Answer 7 · answered Jul 30 '20 at 03:19

In physics: both are acceptable

Native speaker here. In my field, physics, I believe both pronunciations are common and accepted. "Plus or minus" may be slightly more clear and formal, but even in a thesis defense, I doubt anyone would take issue with "plus minus", since the meaning would always be clear from context and they sound similar when spoken aloud anyways. (My pronunciation of ± is closer to "plusserminus" in practice).

Jeff Morrow · Answer 8 · 2020-07-27T21:30:02.283

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What does the "plus/minus" sign mean when used mathematically?

The symbol itself is called typically called a "plus minus sign," but no one will be confused or upset if you say "plus or minus sign."

x = (plus/minus sign) 3 means mathematically (x = +3) V (x = -3), where V stands for the non-exclusive or.

In U.S. schools, it is often taught that the preferred translation into English is "x is equal to positive three or negative three." The reason for that is two fold. First, it closely matches the mathematical definition. Second, it distinguishes between the use of + and - as symbols signifying sign and the use of + and - as symbols signifying the operations of addition and subtraction. Nevertheless, it is very common to hear "x is equal to plus or minus 3." But the "or" word is never dropped because that corresponds to part of the mathematical definition.

y = x (plus/minus sign) 1 means (x = x + 1) V (y = x - 1). It is formally translated in the U.S. as "y equals x plus one or x minus one. Again, this conforms to the mathematical definition. Of course as epi points out, this kind of formal translation is often abbreviated to y = x plus or minus 1. The word "or" is never dropped.

edited Jul 27 '20 at 21:30

answered Jul 27 '20 at 19:58

Jeff Morrow

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I've never seen 10±1 used to mean "9 or 11", only to mean "10 with an expected error of 1". But that's scientific usage rather than mathematical. – Michael Kay Jul 27 '20 at 23:47
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@MichaelKay: ok but 10 + (-1)^n does mean "9 or 11" (when n is an integer) – smci Jul 28 '20 at 08:11
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Expressions like "x = 10 ± 1" meaning x has the value of 9 or 11 (or both simultaneously) are very common in mathematics. The quadratic formula is probably the context where most students will encounter it, and where they would use it most often. Others will see it in statistics. Some may see in other areas. @MichaelKay – Jul 28 '20 at 10:33
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Sorry, but you have this backwards : the symbol may be called "plus-minus" by typographers for brevity, but to an engineer or mathematician it is "the plus or minus symbol", and the latter is surely the correct term in this context. – MikeB Jul 28 '20 at 17:22
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There's also the inverted version (∓), which is used to show an alternation: a±b∓c would be something like a+b-c OR a-b+c (but neither a+b+c nor a-b-c). – Matt Krause Jul 28 '20 at 18:46
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@nij x = 10 ± 1 has the value of 9 or 11 simultaneously is just absurd. Nine and eleven are distinct numbers, and no number is equal to them both at the same time. – Jeff Morrow Jul 28 '20 at 23:33
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When x is defined as "any solution to equation A" and equation A is a quadratic with particular coefficients, yes, x can have two distinct values simultaneously. – Jul 28 '20 at 23:36
@MichaelKay I am not a scientist or engineer, but my understanding was that meaning of f x = 10±1 was 9 < x < 11 and had nothing to do with expected value. In fact, I do not see how an expected value in the mathematical sense can have anything but a unique value – Jeff Morrow Jul 28 '20 at 23:36
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@Nij Go to any math site and ask whether your statement is correct. The solution set to a quadratic equation may have two values. If they are distinct, they are not simultaneously true, The plus/minus sign is read as "plus or minus" rather than "plus and minus." The solution to x^2 - 3x + 2 = 0 is x = 2 or x = 1, not x is equal to 2 and 1 at the same time. There are two different solutions. – Jeff Morrow Jul 28 '20 at 23:40
@MikeBrockington I am confused by your comment if it is addressed to me. It seems to me that I was consistent in using "sign" or "symbol." If you could clarify what you meant, I'd be happy to edit. – Jeff Morrow Jul 28 '20 at 23:44
There are two distinct usages of the symbol. One expresses a confidence interval, appearing in the numeral part of a quantity. It is not quite a range of values, but may be sometimes considered such for certain kinds of analysis. The other usage appears in written equations, to express multiple actual equations within a single written one. Each appearance of the symbol corresponds to two separate equations, each having one or the other sense of the symbol, plus or minus. – brainchild Jul 29 '20 at 08:53
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@JeffMorrow Your second paragraph implies that "plus minus sign" is the _ correct _ term, but it's the reverse: "plus or minus sign" is correct, and "plus minus sign" is a contraction, albeit generally understandable. – MikeB Jul 29 '20 at 11:00
@JeffMorrow This is discussed at https://stats.stackexchange.com/questions/147469/is-it-correct-to-use-plus-or-minus-symbol-before-standard-deviation -- but my scientific training is so long ago that I've quite forgotten the fine distinction between standard error and standard deviation. – Michael Kay Jul 29 '20 at 11:28

score 0 · Answer 9 · answered Jul 27 '20 at 19:43

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Exception: sports statistic

In ice hockey, there is a statistic derived from subtracting the goals scored against while a player is on the ice from the goals scored by the team while the player was on the ice (with some extra complications). This is a rare exception, but in this situation it is pronounced plus-minus. See the wikipedia page. It is also more often written as "+/-" than ±, but still pronounced the same.

answered Jul 27 '20 at 19:43

llama

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"+/-" is a derivation caused by a lack of a designated key for "±" on our standard keyboard. The two forms can be interchanged. – Chris Schaller Jul 28 '20 at 01:38
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Here "plus-minus" simply means "goal difference", just like "net approval rating" in politics. This is pretty generic type of stat, in football (soccer) it's called "goal difference". In soccer it's calculated per-team on a per-game basis, not per-player on a per-minute basis, since unlike hockey, soccer doesn't have rolling substitution and has a much larger team, so essentially everyone would have the same stat except the handful of players that got substituted. – smci Jul 28 '20 at 08:16
@ChrisSchaller - If you were using a proper computer, you could just press "shift+option+=" to get a '±' from your keyboard. Just sayin'. ;-) – MrWonderful Jul 30 '20 at 10:28
I'm not into fruity devices @MrWonderful ;) – Chris Schaller Jul 30 '20 at 13:15

score 0 · Answer 10 · answered Oct 03 '23 at 19:08

the mathematical equation 1 ± 1. We can say "plus or minus one". May I omit "or" to say "plus minus one"?

The expression—not equation—1 ± 1 in mathematics outside of statistics (where, in the context of confidence intervals, it might mean 0 to 2) is short for 1 + (±1), and equals 0 or 2 (it does not equal 0 and 2, because no number can simultaneously have two values). It is read aloud as “1 plus or minus 1”, but for the sake of brevity many of us further—both silently and aloud—shorten it as “1 plus minus 1” with no ill effect.

On a related note: the faux equation x = ±b is mathematical shorthand for the disjunction x=-b or x=b of two equations.

the signed number: ± 1. May I say "plus minus one"?

Since your first query's 1 ± 1 means 1 + (±1), all these ±1s are the exact same object, and are all read aloud as “plus (or) minus 1”.

the signed number: ± 1. We say "positive or negative one".

Although it is rather common to verbalise ± 1 as “positive or negative 1”, this is not technically correct, and “plus (or) minus 1” is the logical and arguably correct verbalisation.

As prefixes, - and ± are unary (as opposed to binary) arithmetic operators: -(-1) (“minus minus 1”) just means to flip the sign of 1 twice. The outer - isn't indicating that -(-1) is negative, while the inner - is indicating neither that 1 is negative nor that 1 has both a positive and a negative version; thus, verbalising -(-1) as “negative negative 1” is neither instructive nor terribly coherent.

Elaboration here.

score -1 · Answer 11 · answered Jul 29 '20 at 18:30

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Assuming you're asking what people say in conversation, most people say "give or take". It's just a casual way to express a tolerance range. It's a common idiom.

answered Jul 29 '20 at 18:30

Anonymous Coward with VPN

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This has the "mathematics" tag on it, so it should be taken as that's the context for when the OP wants to use the phrase. If you had more experience here, I'd down vote. It's easy to miss the tags, but please try to remember them moving forward. (FYI, check out the Tour and Code of Conduct to make sure you don't inadvertently do something wrong to earn down votes.) If it wasn't for the tag, you'd be correct. – computercarguy Jul 29 '20 at 20:11