English Language & Usage Stack Exchange is a question and answer site for linguists, etymologists, and serious English language enthusiasts. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

Since the childhood days we have been memorizing the tables of numbers saying :

two ones are two (2 x 1 = 2)

two twos are four (2 x 2 = 4)

two threes are six (2 x 3 = 6)....

However recently I came across a rule stating that if the mathematical operation of two or more fixed numbers(constants) yields a fixed numeral, then the singular form of verb should be used to denote the operation connecting the operands and the result. This makes the sentence look like :

Two twos is four.

Is it really so??

share|improve this question

marked as duplicate by RegDwigнt Jun 5 '14 at 10:49

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.

Two comments: the rule you are stating is called the closure properties of addition and multiplication also please note, 2 X 3 = 6 not 2 X 2 = 6 – Sᴋᴜʟʟ ᴘᴇᴛʀᴏʟ Jun 5 '14 at 10:00
@skullpatrol - 2 x 2 = 6 for sufficiently large values of 2. :P – oerkelens Jun 5 '14 at 10:04
There is, I believe, a subtle difference between 'two and two make/s four' and 'two and two is four', which is not addressed in the claimed duplicate. – Edwin Ashworth Jun 5 '14 at 10:52

The sentence two twos are four is correct, but although it is a common English phrase, it is not mathematical - in actual mathematics, the equations is not pronounced that way.

In mathematics, the equal sign is pronounced as equals or simply is.

It denotes that everything on the left equals everything on the right, hence the singular.

However, in mathematics, no-one will ever pronounce 2 x 2 = 4 as two twos are four.

Two times two equals four
Two times two is four

Are both acceptable, and indeed, the singular is used to indicate that the parts on the left and the right of the equal sign are seen as complete, whole, singular expressions. (So even 7 times 5 plus 3 divided by 12 minus 2 is seen as a singular expression.)

The simplified two twos are four is in itself correct, as it strays from the strict mathematical domain. It aims at visualizing for children that 2 x 2 = 4 can be seen as two occurrences of a concept "2". In that case, since we are actually counting them, the plural is correct, in exactly the same way as we say

Two horses have 8 legs. (not has!)

share|improve this answer
So what is the answer to the original question ---> Two and two (is /are) not five....? – Maroof Kazmi Jun 5 '14 at 8:37
@MaroofKazmi - the answer to Is this so? is not answerable because it is unclear what this refers to. As I wrote in the last paragraph: "two twos are four is in itself correct". – oerkelens Jun 5 '14 at 8:39
@MaroofKazmi - ah - with "original question you mean your title. I missed that as you title does not appear in your question. It is a good isea top include your question in your actual question text. Well, as I wrote that "two twos are four" is correct in the last paragraph of my answer, I don't see what is unclear about which form to use in your title-sentence :) – oerkelens Jun 5 '14 at 8:43
I upvoted but did take a little while to find _ ... two twos are four is in itself correct, as ..._, it would be more obvious if it were at or near the top of the answer, but at least it is in there. – Frank Jun 5 '14 at 8:55
@JamesRyan: thank you for pointing that out! In my effort to make things more clear so people would not have to read the whole answer I messed it up. Of course, that should be two twos are four is correct! – oerkelens Jun 5 '14 at 9:44

Not the answer you're looking for? Browse other questions tagged or ask your own question.