Which one of these two sentences is grammatical?

(1) For every variable x and y, so and so...

(2) For every variables x and y, so and so...

Grammarly seems to prefer (1), but it sounds strange to my ear...

  • 1
    Those are not sentences.
    – tchrist
    Jan 17 at 18:37
  • 2
    I’m voting to close this question because neither of the texts submitted to Grammarly are meaningful sequences in English. But even if they were, it's not our job to debug Grammarly. Jan 18 at 13:43

3 Answers 3


"every" is an indefinite pronoun and takes a singular noun. e.g; Every man and woman participated in the game. So, " for every variable "x" and "y" is the correct sentence.

  • 1
    Yes. Math norms use "For every variable x and y" or "For all values of x and y." Jan 17 at 19:08

There is a way to use the plural but it uses the word 'all' instead of 'every' giving the phrase "... for all variables x and y ...". If Grammarly genuinely suggests "... for every variables x and y ..." then it is wrong.


In these cases its useful to rewrite the sentence.

For example:

For every variable x and y


For every variable x and for every variable y

It is easier to notice how your second example is incorrect, since it would be rewritten as:

For every variables x and for every variables y


For all variable x and for all variable y

doesn't sound correct, but

For all variables x and for all variables y


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