Number in English Grammar: Types, Rules & Examples

In English grammar, “number” refers to whether a noun, pronoun, or verb form denotes one entity (singular) or multiple entities (plural). Beyond just singular and plural forms, English also uses various categories of numbers—cardinal, ordinal, and fractional—to indicate quantities and order. Mastering these concepts ensures accurate and clear communication, correct subject-verb agreement, and proper use of determiners and pronouns. This guide will thoroughly explain what number means, how to form plurals (including many exceptions), how it affects sentences, and how to correctly handle numerical expressions.

Table of contents

What Is Number in Grammar?

Number in grammar shows whether we are referring to one thing (singular) or more than one thing (plural).

• Singular: Refers to one person, place, thing, or idea.
  • Example: “A book is on the table.”
• Plural: Refers to two or more persons, places, things, or ideas.
  • Example: “Several books are on the table.”

Why It Matters:

• Verbs must agree with their subjects in number: “He runs” vs. “They run.”
• Pronouns must agree in number with their antecedents: “The child lost her toy” vs. “The children lost their toys.”

Singular and Plural Nouns

Nouns can typically be counted (count nouns) and therefore have both singular and plural forms.

General Rule for Pluralization

For most nouns, simply add -s to form the plural:

• car → cars
• dog → dogs
• lake → lakes

Additional Rules and Exceptions

1. Nouns Ending in -s, -sh, -ch, -x, or -z: Add -es
   • bus → buses
   • brush → brushes
   • church → churches
   • box → boxes
   • quiz → quizzes (Note: sometimes the final “z” is doubled before adding “-es”)
2. Nouns Ending in Consonant + y: Change “y” to “i” and add -es
   • baby → babies
   • city → cities
   • party → parties
3. Nouns Ending in Vowel + y: Just add -s
   • key → keys
   • toy → toys
4. Nouns Ending in -f or -fe: Often change “f” to “v” and add -es
   • leaf → leaves
   • wife → wives
   • knife → knives
   Exceptions: Some simply add “-s”:
   • roof → roofs
   • cliff → cliffs
   • belief → beliefs
5. Nouns Ending in -o: This rule can be tricky. Many nouns ending in “-o” add “-es,” but some just add “-s.”
   • Add -es: hero → heroes, potato → potatoes, echo → echoes
   • Add -s: piano → pianos, photo → photos, memo → memos Tip: Many borrowed words or shorter words ending in “o” just take “-s”.
6. Irregular Plurals: Some nouns have completely irregular plural forms:
   • man → men
   • woman → women
   • child → children
   • foot → feet
   • tooth → teeth
   • goose → geese
   • mouse → mice
   • louse → lice
   • person → people (or persons in formal/legal contexts)
7. Nouns That Do Not Change: Some nouns have the same form in singular and plural:
   • sheep → sheep
   • deer → deer
   • fish → fish (though “fishes” can be used to emphasize different species)
   • series → series
   • species → species
   • aircraft → aircraft
8. Latin or Greek Origin Nouns: These sometimes retain their original plural forms:
   • cactus → cacti (or cactuses)
   • fungus → fungi (or funguses)
   • nucleus → nuclei
   • alumnus → alumni (alumna → alumnae for female)
   • criterion → criteria
   • phenomenon → phenomena
9. Compound Nouns: For compound nouns, generally pluralize the main word:
   • mother-in-law → mothers-in-law
   • passer-by → passers-by
   • commander-in-chief → commanders-in-chief
10. Letters, Numbers, and Symbols: Add “-s” (or ’s for clarity) to form the plural of letters and symbols:
    • “Mind your p’s and q’s.”
    • “Add two 7’s to the list.” (Or “7s”)

Uncountable (Non-Count) Nouns and Number

Some nouns represent substances, qualities, or concepts that can’t be divided into countable units. These are uncountable nouns and typically have no plural form:

• water, information, furniture, advice, music, rice

These nouns:

• Remain singular.
• Take singular verbs: “The information is helpful.”
• Require measure words or phrases to quantify: “a piece of information,” “two liters of water.”

Subject-Verb Agreement with Number

A verb must agree in number with its subject:

• Singular subject → singular verb
  “The girl runs fast.”
• Plural subject → plural verb
  “The girls run fast.”

Third-Person Singular (he, she, it):
Add “-s” or “-es” to the base form of the verb:

• He runs, she watches, it goes

Plural Subjects and I/You:
Use the base verb form:

• They run, we watch, I work, you play

Collective Nouns:
Collective nouns (family, team, jury) can be singular or plural depending on context:

• As a single unit: “The team is winning.”
• As individuals: “The team are arguing among themselves.”

Pronouns and Number

Pronouns must match the noun’s number:

• Singular pronouns: I, you (singular), he, she, it
• Plural pronouns: we, you (plural), they

Examples:

• Singular: “The student lost her book.”
• Plural: “The students lost their books.”

Singular ‘They’:
Modern usage allows “they” for a singular, gender-neutral antecedent:

• “Someone left their coat.”
• “Each person must bring their ID.”

Types of Number Words: Cardinal, Ordinal, and More

English includes numerical expressions for quantity, order, fractions, and more.

1. Cardinal Numbers (one, two, three…):
   Indicate quantity.
   • “There are three apples.”
2. Ordinal Numbers (first, second, third…):
   Indicate order or position.
   • “She finished first in the race.”
3. Fractions and Decimals:
   Show parts of a whole or precise measurements.
   • Fractions: half, one-third, two-fifths
   • Decimals: 1.5 (one point five), 2.75 (two point seven five)
4. Multiplicative Numbers:
   Indicate frequency or repetition.
   • once, twice, three times

Using Numbers as Adjectives and Nouns

Numbers often function as adjectives (or determiners) when placed before nouns to indicate how many:

• “I have two dogs.”
• “She needs three chairs.”

Numbers can also be treated as nouns in some contexts:

• “Seven is my favorite number.”
• “A dozen equals twelve.”

Special Considerations

1. Singular “They”:
   Accepted in both informal and increasingly in formal contexts to be inclusive and gender-neutral.
2. Numbers in Writing:
   • Spell out numbers from zero through nine in formal writing.
   • Use numerals for 10 and above, except at the start of a sentence.
   • Use ordinal numbers spelled out for formal text: “He came in second.”
3. Units of Measurement:
   • Before a noun, use a singular unit even if the number is plural: “A five-meter pole” (not “five-meters pole”).
   • After the noun, pluralize units: “The pole is five meters long.”
4. Count vs. Non-Count Nouns:
   • Some words can be both count and non-count depending on context:
     • “Two coffees, please.” (Here coffees = cups of coffee)
     • “Coffee is grown in many countries.” (Non-count form)

Additional Pluralization Exercises

1. loaf → ________
2. tomato → ________
3. hero → ________
4. mouse → ________
5. radius → ________

Answers:

1. loaves
2. tomatoes
3. heroes
4. mice
5. radii (or radiuses accepted in modern usage)

Subject-Verb Agreement Exercise

Select the correct form of the verb:

1. “My family (is/are) from New York.”
2. “Each of the students (has/have) a notebook.”
3. “The data (is/are) accurate.” (Note: In modern usage, “data” can be singular or plural depending on style.)
4. “The team (wins/win) when they work together.” (Singular if team as a unit, plural if emphasizing individuals)

Suggested Answers:

1. is (family acting as a single unit)
2. has (each is singular)
3. is (common usage treats data as uncountable singular)
4. wins (if the team is viewed as one unit)

Conclusion

Number is a fundamental concept in English grammar that affects how we form plural nouns, choose pronouns, and maintain subject-verb agreement. It also influences how we discuss quantities, orders, and measurements using numerical expressions. By learning the many rules for plural formation, understanding uncountable nouns, and practicing with various examples, you can master number usage and ensure your English is precise, clear, and grammatically correct.