Understanding ‘Number’ in English Grammar

In English grammar, Number tells us whether a noun or pronoun refers to one (singular) or more than one (plural).
It is an essential concept because:

• It controls noun forms.

• It determines verb agreement.

• It influences pronoun choices.

• It contributes to the accuracy and clarity of sentences.

Why Students Must Master This?

In Sainik School, RMS, and Navodaya exams, questions are often asked on:

• Plural formation rules

• Irregular plurals

• Subject–verb agreement

• Error spotting

• Change of number in sentences

Strong conceptual clarity ensures high accuracy in grammar-based questions.

2. Singular and Plural: Basic Definitions

3. Most Basic Rule

✔ Add –s to most singular nouns to make them plural.

• book → books

• chair → chairs

• cat → cats

This is the foundation. Almost all learners start from here.

4. 10 Golden Rules for Changing Singular to Plural

Below are the most important NCERT-based rules every student must memorize.

📘 Rule 1: Add -s to Most Nouns

This is the simplest plural formation.

• car → cars

• pen → pens

• flower → flowers

Tip: If the word ends in a plain letter, just add -s.

📘 Rule 2: Add -es to Nouns Ending in s, sh, ch, x, or o

These sounds need an extra syllable; hence, -es is added.

• bus → buses

• church → churches

• box → boxes

• mango → mangoes

• brush → brushes

Remember: Most words ending in o take -es, but not all (explained later).

📘 Rule 3: Consonant + y → Replace y with i and Add -es

• baby → babies

• lady → ladies

• city → cities

Reason: The consonant before y causes the spelling to change.

📘 Rule 4: Vowel + y → Just Add -s

• boy → boys

• toy → toys

• key → keys

No spelling change because vowels keep the y stable.

📘 Rule 5: Words Ending in f or fe → Change to -ves

• leaf → leaves

• thief → thieves

• wife → wives

• knife → knives

Note: Some exceptions exist (chief → chiefs, roof → roofs).

📘 Rule 6: Nouns Ending in ‘o’ – Either -s or -es

Take -es

• potato → potatoes

• tomato → tomatoes

Take -s

• photo → photos

• piano → pianos

👉 These must be memorized. NCERT and exam MCQs frequently test them.

📘 Rule 7: Irregular Plurals (No Fixed Rule)

These words change completely and must be learned by heart.

• man → men

• woman → women

• child → children

• tooth → teeth

• mouse → mice

• goose → geese

• ox → oxen

Irregular plurals often appear in error spotting.

📘 Rule 8: Some Nouns Remain the Same in Singular and Plural

Their form does not change.

• deer → deer

• sheep → sheep

• aircraft → aircraft

• species → species

Tip: Context will tell whether they are singular or plural.

📘 Rule 9: In Compound Nouns, Add -s to the Main Word

Identify the principal noun and pluralize it.

• mother-in-law → mothers-in-law

• passer-by → passers-by

• commander-in-chief → commanders-in-chief

📘 Rule 10: Some Nouns Are Always Used in the Plural

These objects consist of two parts—so they appear only in plural.

• trousers

• scissors

• spectacles

• pliers

• shoes

When using them, write:

• a pair of trousers/scissors/shoes

5. Special Plurals with Distinct Meanings

Some nouns have different plurals with different meanings (important for exams).

Example:

• “The peoples of Africa” = different tribes/nations.

• “I bought ten pennies” = individual coins.

6. Change of Number in Sentences

When a noun changes number, related words must also change.

Change:

• Verbs → is/are, has/have

• Demonstratives → this/these, that/those

• Pronouns → he/they, she/they, it/they

• Articles/Quantifiers → a/some, much/many

Examples

7. Complete List of Irregular Plurals You Must Memorize

Note: Some are from higher classes but useful in competitive exams.

8. Common Exam Mistakes to Avoid

❌ Don’t pluralize uncountable nouns:

• informations → incorrect

• advices → incorrect

• furnitures → incorrect

Correct:
✔ information, advice, furniture

❌ Don’t add plural to adjectives:

• the poor people → ✔ the poor

• the rich persons → ✔ the rich

❌ Don’t confuse plural verbs:

• The data is correct → ❌

• The data are correct → ✔ (formal rule)