In mathematics one will often say "This plus that" or "This times that". This means "This added too that" and "This multiplied by that".

Multiply, Add, Subtract, Divide - All are verbs. But what part of speech is "times" or "plus". It's wrong to say "times this by that" or "plus this with that". So they do not seem to be verbs, but they imply an action.

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    As you will have observed by now, identifying the "part of speech" of a particular word tells you nothing about the grammar, and is always fraught with disagreement, because the usual list of the Classical Eight was developed at about the same time as the Crusades for a different language, and suits modern English somewhat worse than English spelling does. So, whatever you decide, nothing useful has been discovered. However, it may please your teacher. Nov 19, 2013 at 0:33
  • Actually, its just helpful when yelling about people for says that they "timesed something" - I can now explain exactly why they are wrong. . .
    – zeel
    Nov 19, 2013 at 1:23
  • But they weren't wrong. They were just talking like mathemeticians talk (I used to socialize with the editors of Math Reviews). I would hope that you would not yell at people about what they say in English, because that's rude and incorrect behavior. Especially if they're your students and have paid for teaching, not abuse. Most especially if they demonstrate their mastery of mathematics and you put them down about something irrelevant; that's poor practice, in any class. Nov 19, 2013 at 16:22
  • Just hyperbole. . .
    – zeel
    Nov 19, 2013 at 20:19
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    @John Lawler: Sorry, the mathematicians managing your annuity funds missed a digit off your last cheque. (But it was only a zero.) Nov 20, 2013 at 22:17

2 Answers 2


M-W defines plus (definition 3, used in addition) as a preposition.

This would make sense if you think of "Three plus four" as "Three added to four."

Alternatively, you could hedge your bets and call the operator a conjunction, which would make sense if you think of "Three plus four" as "Three and four."

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    So then "plus" dose not imply an action, instead it implies a relationship.
    – zeel
    Nov 18, 2013 at 17:31
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    If I say 'Apple pie with custard is nice', 'with' is a preposition. So what if I say 'apple pie and custard' is nice? You might argue that 'and' is a conjunction. Well it would be if you meant that both apple pie and custard in their separate ways were both nice. But then you would have to replace 'is' with 'are'. But what is being said is that apple pie and custard, taken together, is nice. And that makes 'and' into a preposition, I believe. So in 'three and four make seven' 'and' is a preposition, the same as 'plus' in 'three plus four'.
    – WS2
    Nov 18, 2013 at 17:46
  • Point taken, @WS2. Out of curiosity, in your flavor of BE, do you say "Two plus two are four" (plural verb) or "Two plus two is four"?
    – rajah9
    Nov 18, 2013 at 18:06
  • @zeel, By definition, an equation is saying that the left-hand side is equal to the right-hand side. It is stating a relationship between the two sides. But at the same time, the plus, minus, times, and divides are called "operators." An operation is happening on those numbers or variables, implying an action.
    – rajah9
    Nov 18, 2013 at 18:11
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    @DanielR.Collins I'm not sure why "As a mathematician" you could consider "three and four" to be linguistically incorrect. Yes, it is still done in elementary schools, but it is hardly an abuse. You may as well heap scorn on Danny Kaye and Sesame Street for the Inchworm song: en.wikipedia.org/wiki/Inchworm_(song). Let's sing it together... "Two and two are four / Four and four are eight"
    – rajah9
    Jan 29, 2016 at 23:50

If I say 'Jelly with ice-cream is nice', it seems to follow the same structure as 'One plus two equals three'.

So in the sentence 'One plus two equals three', 'One plus two' I would have said was a subject clause, 'equals' is the verb, and 'three' is the predicate.

Therefore in the context 'plus' seems to me to be a preposition, equivalent to 'with' in 'jelly with ice-cream'.

  • But if we consider 'one add / plus two (equals)' to be a shortened form of '(when) two is added to one (the result is)', we can draw up different equivalences. Nov 19, 2013 at 21:18

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