Is "Number" Singular or Plural?

The Quick Answer
The term number of is nearly always plural. (e.g., A number of workers have left.)

When used as a noun referring to an arithmetical value, the word number is singular. (e.g., The number has risen. The number of votes is six.)


The word number is singular when it refers to an arithmetical value expressed by a word or symbol. (When used like this, it is a common noun.)

  • The number is likely to rise.
  • The letter is an A, but the number is hard to determine.

Number Of

The word number is not always a common noun. It can also be an indefinite pronoun meaning some. In this meaning (usually seen in the format a number of), it is plural.

  • A number of factors are to be considered.
  • There are still a number of toads under the shed.
  • There is still a number of weeds to remove.

Indefinite Pronouns Can Take a Singular or Plural Verb

Number follows the same ruling used with the indefinite pronouns all, any, more, most, and some. These are singular when they refer to something singular (i.e., a non-countable noun) but plural when they refer to something plural (i.e., a countable noun). For example:
  • Some of the cheese has gone moldy.
  • Some of the biscuits have gone moldy.
Therefore, the term a number of will always be plural because the object of the preposition of (i.e., the word that follows of) will be plural. (If it isn't, then you're not using number correctly.)

Don't forget though, number can be a singular noun referring to an arithmetical value.
  • The number of votes was twenty-two.
  • The number of votes were twenty-two.

See Also

Subject-verb agreement Are collective nouns singular or plural? Singular or plural verbs after prepositional phrases (e.g. a box of tapes)