Numbers
Learn how cardinal numbers, such as three, and ordinal numbers, such as third, come before a noun to show an exact quantity or an exact position.
One, two, three. First, second, third.
A number determiner gives an exact quantity or position.
A number is a determiner that comes before a noun to show exactly how many there are, or exactly where something falls in a sequence.
In the sentence She has three sisters., the word three is a number determiner. It gives the exact quantity of sisters, rather than a general amount.
English uses two kinds of numbers before nouns: cardinal numbers, which count, and ordinal numbers, which show position or order.
Before you begin
Numbers are one category of determiner.
This lesson focuses on numbers specifically. If you would like an overview of how determiners work as a whole topic, begin with the Determiners page.
The central idea
A number gives an exact amount, not a general one.
Compare a general quantifier with an exact number.
01
A General Amount
Gives an approximate idea of quantity.
She has several sisters.
02
An Exact Number
States the precise quantity.
She has three sisters.
The useful question is: How many exactly, or which one exactly?
three sisters → exact quantity
third sister → exact position among the sisters
A cardinal number answers “how many?” precisely. An ordinal number answers “which one, in order?”
Cardinal numbers
Cardinal numbers count, and they decide whether the noun is singular or plural.
One takes a singular noun
I only need one chair.
Two or more takes a plural noun
I need three chairs for the meeting.
Any cardinal number above one is followed by a plural noun.
Cardinal numbers can combine with other determiners
I finished my three tasks before lunch.
Here, the possessive my and the number three appear together before the noun.
Ordinal numbers
Ordinal numbers show position or order.
Most ordinal numbers add -th
four → fourth
six → sixth
ten → tenth
A few ordinal numbers are irregular
one → first
two → second
three → third
five → fifth
nine → ninth
twelve → twelfth
This is my first visit to the city.
Ordinal numbers need a determiner of their own
An ordinal number is almost always paired with another determiner.
Ordinal numbers with the
The second chapter was the most interesting.
Ordinal numbers with a possessive
This was her third attempt at the exam.
Unlike cardinal numbers, ordinal numbers are rarely used entirely on their own before a noun.
Using both types together
An ordinal number usually comes before a cardinal number.
Ordinal before cardinal
Please read the first three chapters tonight.
First identifies which chapters, in order, and three gives the exact number of them.
Numbers and quantifiers
Numbers are exact. Quantifiers are usually approximate.
Words such as several, many and a few give a general sense of amount, while a number states the amount precisely.
several sisters → an approximate amount
three sisters → an exact amount
This distinction is explored fully in the Quantifiers lesson.
A useful decision guide
Ask whether you need a quantity or a position.
01
Do you need to state an exact quantity?
Use a cardinal number, such as one, two or three.
02
Do you need to show position in a sequence?
Use an ordinal number, such as first, second or third.
03
Is the cardinal number exactly one?
Use a singular noun; any number above one needs a plural noun.
04
Is an ordinal number being used?
Pair it with the or a possessive, since it rarely stands alone before a noun.
Common mistakes
Do not mismatch a number’s form with the noun that follows.
Using a plural noun after “one.”
Not: I only need one chairs.
Correct: I only need one chair.
One always takes a singular noun.
Leaving out the determiner before an ordinal number.
Not: Second chapter was the best.
Correct: The second chapter was the best.
Ordinal numbers are almost always paired with another determiner.
Misspelling an irregular ordinal number.
Not: fiveth, nineth, twelveth
Correct: fifth, ninth, twelfth
A small group of ordinal numbers change spelling in ways that must be learned individually.
Check your understanding
Cardinal or ordinal?
Choose the correct description for the highlighted number.
She adopted two kittens last month.
✅ Exactly! Two gives an exact quantity.
❎ Not quite. Ask whether this word counts, or shows position in a sequence.
Does this word answer “how many,” or “which one in order”?
This is her fourth attempt at the driving test.
✅ Exactly! Fourth shows position among a series of attempts.
❎ Not quite. This word shows which attempt, in order, not a simple count.
Which is correct?
✅ Exactly! One always takes a singular noun.
❎ Not quite. Think about the number of chairs being described.
This is __________ time I’ve called about this issue.
✅ Exactly! An ordinal number needs a determiner such as the.
❎ Not quite. Ordinal numbers are almost always paired with another determiner.
Choose the best explanation
Select the sentence that explains the number correctly.
Why does “one chair” use a singular noun?
✅ Exactly! Only one takes a singular noun; every other cardinal number needs a plural noun.
❎ Not quite. Think about what type of number one is.
Why does “the first three chapters” put first before three?
✅ Exactly! The ordinal number identifies which group, and the cardinal number states how many are in it.
❎ Not quite. Both numbers are working together in this phrase.
Which sentence correctly uses an ordinal number?
✅ Exactly! Fifth is spelled correctly and paired with the determiner the.
❎ Not quite. Check both the spelling of the ordinal number and whether it has a determiner.
Try it another way
Complete the sentence with the correct number.
Type a cardinal or ordinal number to complete each sentence.
✅ Exactly! This is a straightforward cardinal number.
❎ Not quite. Write the cardinal number for 2.
✅ Exactly! Eight becomes eighth in the ordinal form.
❎ Not quite. Add the ordinal ending to the number 8.
✅ Exactly! Nine becomes the irregular ordinal form ninth.
❎ Not quite. This ordinal number drops a letter before adding -th.
Edit the sentence
Rewrite each sentence with the correct number or noun form.
Use the note in brackets to decide what needs to change.
I only need one chairs for the corner. (correct the noun)
✅ Exactly! One always takes a singular noun.
❎ Not quite. Change the noun to its singular form.
Second chapter was the best. (add the missing determiner)
✅ Exactly! An ordinal number needs a determiner such as the.
❎ Not quite. Add the before the ordinal number.
My fiveth attempt finally worked. (correct the spelling)
✅ Exactly! Five forms the irregular ordinal fifth.
❎ Not quite. Correct the spelling of the ordinal form of five.
Quick review
Cardinal numbers count. Ordinal numbers order.
Cardinal numbers — one, two, three — state an exact quantity, deciding whether the following noun is singular or plural.
Ordinal numbers — first, second, third — state an exact position in a sequence.
Most ordinal numbers add -th; a small group, including first, second, third, fifth, ninth and twelfth, are irregular.
An ordinal number is almost always paired with another determiner, such as the or a possessive.
When both types appear together, the ordinal number usually comes before the cardinal number, as in the first three.
Numbers give an exact amount; quantifiers such as several give a general one.
Remember
Ask whether you are counting or ordering.
A cardinal number counts and decides the noun’s number. An ordinal number places something in a sequence and almost always needs a determiner of its own alongside it.