"two is"

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Hello samurai, and welcome to English Forums.

The writer could have used 'are' but 'is' indicates that s/he is thinking of a single quantity rather than a number of units.
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The nouns to which the "is" is referring to, are all singular compound nouns, hence the use of the singular verb "is".
"two", "three", etc are compound nouns in the singular.
Same as other compound singular nouns like crowd, flock (of birds), school (of fish), group,

You can talk of these in the plural, eg crowds, flocks, etc, and also twos, threes, and fours.
Then they tak

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Could you give us your definition of 'compound noun', Jeannie?
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I think of it like an adjusting lever, or ****. "Two clicks is not enough." "Four turns is way too much." (That is, too much adjustment.)

Edit. Hmm. I'm running into an antecedent problem here. Not the compound noun.

Thanks for the pick-up. I meant collective nouns.
"A collective noun denotes a collections of groups of individuals" as per the examples I gave.
In some collective nouns the idea of the singleness, the unity of the group, is uppermost, and these works are always regards as singular. They require the singular form of the verb."
"Though the collective noun is singular and ought to tak