Cardinal Numbers

Overview

Cardinal numbers (1, 2, 3…) express quantity — they answer the question "how many?" They are the most basic and frequently used numbers in English, appearing in counting, measurements, ages, prices, times, and more.

1. Numbers 1–20

Number	Word	Number	Word
1	one	11	eleven
2	two	12	twelve
3	three	13	thirteen
4	four	14	fourteen
5	five	15	fifteen
6	six	16	sixteen
7	seven	17	seventeen
8	eight	18	eighteen
9	nine	19	nineteen
10	ten	20	twenty

Spelling notes:
- 13–19: most end in -teen (but note: thir-teen, fif-teen, eigh-teen, nine-teen)
- 12 = twelve (irregular)

2. Tens: 20–100

Number	Word	Number	Word
20	twenty	60	sixty
30	thirty	70	seventy
40	forty	80	eighty
50	fifty	90	ninety
100	one hundred

Note: forty (not ~~fourty~~), eighty (not ~~eightty~~)

3. Compound Numbers (21–99)

Use a hyphen between tens and units.

Number	Word
21	twenty-one
35	thirty-five
48	forty-eight
99	ninety-nine

4. Hundreds, Thousands, Millions

Number	Word
100	one hundred
200	two hundred
365	three hundred and sixty-five
1,000	one thousand
5,280	five thousand two hundred and eighty
1,000,000	one million
2,500,000	two million five hundred thousand

Note: In British English, use "and" after "hundred": three hundred and sixty-five.
In American English, "and" is often omitted: three hundred sixty-five.

5. Using Cardinal Numbers with Nouns

Pattern	Example
Number + plural noun	three books, twenty students
Number + singular (= 1)	one apple, a cup
One hundred / a hundred	Both are correct

I have two sisters and one brother.

The building has thirty-five floors.

There are one hundred students in the hall.

6. Special Uses

Telephone numbers — say each digit individually

0800 → "oh eight hundred" (UK) / "zero eight hundred" (US)

Prices

£4.99 → "four pounds ninety-nine"

$2.50 → "two dollars fifty"

Ages

She is twenty-three years old.

Years

1990 → "nineteen ninety"

2005 → "two thousand and five"

2024 → "twenty twenty-four"

7. Common Mistakes

Mistake	Correction	Explanation
fourty	forty	No "u" in forty
five hundreds	five hundred	Hundred/thousand/million never take -s in compound numbers
twenty one	twenty-one	Hyphen required
She has twenty years	She is twenty (years old)	Use "is" for age
one thousands	one thousand	No plural after a number

8. Real-World Examples

There are seven days in a week and twelve months in a year.

My phone number is zero seven nine three four (07934…).

The ticket costs forty-five pounds.

She moved to London twenty-three years ago.

Summary

Range	Pattern	Example
1–12	Unique words	one, two… twelve
13–19	Root + -teen	thirteen, fifteen
20–90	Root + -ty	twenty, fifty
21–99	Tens-units (hyphen)	thirty-four
100+	Number + hundred/thousand + and	three hundred and twelve