41

From here

I thought:

  1. mathematical equation: 1 ± 1 - We can say "plus or minus one". Could I omit "or" to say "plus minus one"?
  2. 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.

  • 10
    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/. – James Wood Jul 27 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 at 2:25
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    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 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 at 18:19
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    'Plus or minus' is completely correct and cannot be misunderstood. – Tom Jul 29 at 22:01

10 Answers 10

58

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)

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  • 10
    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 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 at 5:38
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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 at 10:55
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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? – Devil's Advocate Jul 28 at 13:57
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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 at 14:38
55

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".

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  • 12
    As an engineer and a native English speaker I'd beg to differ. You absolutely can just say "plus minus X". – Persistence Jul 29 at 13:47
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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 at 16:19
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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 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 at 19:00
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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 supports MonicaC Jul 30 at 3:57
24

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.

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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 at 15:28
22

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.

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  • 16
    en.wikipedia.org/wiki/Plus%E2%80%93minus_sign and 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 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 at 20:22
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    x+(-1) should be said as "x plus negative one". – Acccumulation Jul 28 at 1:41
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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 supports MonicaC Jul 28 at 4:57
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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. – Devil's Advocate Jul 28 at 14:01
13
  1. mathematical equation : 1 ± 1 , we can say plus or minus one , could I omit or to say plus minus one?
  2. a signed mathematical number: ± 1, we say positive or negtive one , but could I say plus minus one here?
  1. No. If you omit the or, it will become ambiguous.

  2. No.

Correct: plus or minus.

Incorrect: plus minus.

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  • 13
    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 at 18:06
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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 at 23:43
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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 at 1:31
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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 at 3:38
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    For me, as a Br. Eng. speaker, this is the correct answer. – Greenonline Jul 28 at 13:09
13

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.

Screenshot of the Google Ngram graph

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  • 5
    Finally, someone with evidence beyond anecdote. Someone buy this answerer a beer! – Cory Klein Jul 29 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 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 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. – epl Jul 30 at 8:36
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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 at 11:12
3

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).

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1

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.

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  • 4
    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 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 at 8:11
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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 – Nij Jul 28 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. – Mike Brockington Jul 28 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 at 18:46
0

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.

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  • 1
    "+/-" 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 at 1:38
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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 at 8:16
  • @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 at 10:28
  • I'm not into fruity devices @MrWonderful ;) – Chris Schaller Jul 30 at 13:15
0

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.

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  • 1
    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 at 20:11

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