Cardinal Numbers in English

In Brief

Cardinal numbers tell you how many: zero, one, two, three and so on. From 21 to 99, write a hyphen between the tens and ones when the last digit is not zero: twenty-one, fifty-five, but twenty and fifty. The standard beginner form for 100 is one hundred.

Overview

Cardinal numbers are the ordinary counting numbers used for quantities, ages, prices, addresses, scores, and many other facts. Three books, twenty euros, and She is forty all use cardinal numbers. The word cardinal simply distinguishes these forms from ordinal numbers, which show position or order: first, second, third.

Numbers up to 100 are an A1 foundation. The system is mostly regular once you know the special forms from 0 to 19 and the words for the multiples of ten. However, spelling and pronunciation can cause problems: thirteen and thirty look similar, forty is not spelled with four, and compound numbers such as sixty-eight need a hyphen when written as words.

English-language explanations normally show numbers in two ways. A numeral is the symbol, such as 27; a number word is the written form, such as twenty-seven. In everyday writing, both are common. This article focuses on how to form, say, and use the words.

How It Works

Zero to ten

These basic forms must be learned individually.

Numeral	Number word	Pronunciation reminder
0	zero	Begins with a z sound
1	one	Sounds like won
2	two	The w is silent
3	three	Begins with the th sound in think
4	four	Sounds like for
5	five	—
6	six	—
7	seven	—
8	eight	Sounds like ate
9	nine	—
10	ten	—

When a number modifies a countable noun (something you can count separately), use a plural noun after every number except one: one ticket, but zero tickets, two tickets, and ten tickets.

Eleven to nineteen: the teens

Eleven and twelve are unique forms. From 13 to 19, most words end in -teen.

Numeral	Number word	Important spelling point
11	eleven	Unique form
12	twelve	Unique form
13	thirteen	Compare three
14	fourteen	Compare four
15	fifteen	Not five-teen
16	sixteen	—
17	seventeen	—
18	eighteen	Only one t in the middle
19	nineteen	—

In clear speech, -teen normally carries the stronger stress: thirTEEN, fourTEEN, fifTEEN. This helps distinguish the teens from the tens, where the first part is normally stronger: THIRty, FORty, FIFty. Rhythm and context can change the stress, so listen to the whole number rather than depending on stress alone.

The tens

The multiples of ten from 20 to 90 end in -ty.

Numeral	Number word	Common contrast
20	twenty	twelve is 12
30	thirty	thirteen is 13
40	forty	Never fourty
50	fifty	Not fivety
60	sixty	sixteen is 16
70	seventy	seventeen is 17
80	eighty	Not eightty
90	ninety	Keeps the e from nine; not ninty

Compound numbers from 21 to 99

For a number that is not an exact multiple of ten, say the tens first and then the ones:

tens + ones

• 21 = twenty-one
• 34 = thirty-four
• 55 = fifty-five
• 68 = sixty-eight
• 99 = ninety-nine

When these numbers are written as words, put a hyphen between the two parts. Do not add and: 42 is forty-two, not forty and two. Exact tens have no second part and therefore no hyphen: twenty, sixty, ninety.

One hundred

The standard full form of 100 is one hundred. After an exact number, hundred stays singular:

• 100 = one hundred
• 200 = two hundred, not two hundreds
• 500 = five hundred

For the A1 pattern, learn one hundred rather than adding an article: There are one hundred pages. In ordinary conversation, a hundred can also mean exactly or approximately 100: I have told you a hundred times. This is natural, but one hundred is clearer when stating or counting an exact number.

Numbers before nouns and numbers used alone

A number can appear directly before a noun: six chairs, twenty students, one hundred pages. It does not change form for singular or plural. The noun carries the contrast: one chair versus two chairs.

A number can also stand alone:

• “How many tickets do you need?” “Three.”
• “What is ten plus five?” “Fifteen.”
• “How old is Maya?” “Twenty-one.”

Do not use years after be when stating an age: Maya is twenty-one, or Maya is twenty-one years old. The form Maya is twenty-one years is incomplete.

Examples in Context

English	Meaning in plain English	Note
I have one sister and two brothers.	My family includes one sister and two brothers.	Quantities before plural and singular nouns
There are zero messages in my inbox.	My inbox has no messages.	Zero takes a plural noun here
The bus arrives in twelve minutes.	The waiting time is 12 minutes.	Basic number before a noun
We need thirteen chairs.	The required quantity is 13 chairs.	Teen number
The class has thirty students.	There are 30 students in the class.	Exact multiple of ten; no hyphen
Her apartment has twenty-one windows.	The apartment contains 21 windows.	Compound number with a hyphen
This jacket costs fifty-five dollars.	The price is $55.	Compound number in a price
My grandfather is eighty.	My grandfather is 80 years old.	Age used after be
Room forty-two is on the second floor.	The room numbered 42 is upstairs.	Identifying a numbered room
Ninety-nine plus one is one hundred.	99 + 1 = 100.	Exact 100
The book has one hundred pages.	The book is 100 pages long.	Hundred remains singular
“How many people came?” “Seventeen.”	A total of 17 people came.	Number used alone

Common Mistakes

Leaving out the hyphen

• Wrong: twenty one, fifty five
• Right: twenty-one, fifty-five
• Why: In standard written English, compound cardinal numbers from 21 to 99 have a hyphen. Exact tens such as twenty do not.

Confusing teen numbers and tens

• Wrong: “The ticket is thirteen dollars” when the price is $30.
• Right: “The ticket is thirty dollars.”
• Why: Thirteen means 13; thirty means 30. Practise the different endings and stress: thirTEEN versus THIRty.

Misspelling forty

• Wrong: fourty
• Right: forty
• Why: Although 4 is four and 14 is fourteen, 40 loses the u. Forty is one of the most frequent number spelling errors.

Adding “and” inside a number below 100

• Wrong: sixty and eight
• Right: sixty-eight
• Why: From 21 to 99, connect the tens and ones directly. And may connect separate items—sixty adults and eight children—but it is not part of the number 68.

Making “hundred” plural after an exact number

• Wrong: three hundreds people
• Right: three hundred people
• Why: After one, two, three, and other exact numbers, hundred does not take plural -s.

Using a singular noun after zero or a number above one

• Wrong: zero message; twenty-one student
• Right: zero messages; twenty-one students
• Why: Use the singular after one and the plural after other cardinal numbers in ordinary counting.

Usage Notes

In running text, style guides often prefer words for short, simple numbers and numerals for measurements, statistics, dates, or longer numbers. You may see both three questions and 3 questions. The grammatical meaning is the same; follow the style expected in your school, workplace, or publication, and stay consistent.

For telephone numbers, codes, and account numbers, speakers usually read the digits separately: 507 can be five zero seven. In British English, oh is also common for zero in phone numbers: five oh seven. In sports, zero may be called nil (two–nil in football), and in tennis it is love. These are context-specific alternatives, not replacements for zero in normal counting.

British and American English differ more noticeably above 100. British speakers commonly include and in 125: one hundred and twenty-five. American speakers often say one hundred twenty-five. This difference does not affect numbers below 100, and both varieties say twenty-five, not twenty and five.

When a cardinal number identifies a label rather than a quantity, it often comes after the noun: Room 12, page 30, Bus 57, Chapter 4. Read these naturally as room twelve, page thirty, bus fifty-seven, and chapter four.

Beyond the Basics / Advanced Use

You do not need to master these details at A1, but they explain forms you will meet later.

For approximate large quantities, English can use a plural number word followed by of: hundreds of people. Compare this with an exact quantity: three hundred people. The patterns cannot be mixed: not three hundreds of people.

In formal compound modifiers, number expressions before a noun are often hyphenated as a unit: a twenty-one-year-old student and a one-hundred-page book. The noun inside this modifier stays singular (year, page). After the verb, use the ordinary phrase instead: The student is twenty-one years old; The book is one hundred pages long.

Decimals use point, followed by separate digits: 3.14 is three point one four. Percentages use percent in American English and often per cent in British English: fifty percent or fifty per cent. These extend the same cardinal-number system but belong to later work with measurements and data.

Dates usually use ordinal numbers—numbers that show order—even though dates are often written with numerals. July 4 can be read July fourth in American English or the fourth of July in British English. Do not normally read it as July four in careful standard speech. The forms first, second, and third are irregular; most later ordinals end in -th. Study the full pattern in the related article on ordinal numbers.

Finally, one can work as more than a number. In the red one, it replaces a previously mentioned countable noun: the red one means “the red item.” That use belongs to pronoun-like substitution rather than basic counting, but it is very common.

Practice Tips

1. Build the pattern aloud. Count 0–20, then say the tens from 20 to 100. Finally choose random numerals such as 24, 37, 58, and 91 and form each number without counting up to it.
2. Train teen–ty pairs. Record yourself saying thirteen–thirty, fourteen–forty, fifteen–fifty, and so on. Then listen back and check whether the ending and stress make each number clear.
3. Use real information. Read prices, ages, room numbers, scores, and page numbers around you in English. When writing number words, check the spelling of forty, fifty, and eighty and add hyphens to compound forms.

Related Concepts

• Next step: Ordinal Numbers — learn first, second, third, and the forms used for dates and order.
• Next step: Telling Time — use cardinal numbers to say hours and minutes in everyday conversation.