How to Write Numbers in English?

Writing numbers correctly is an important part of clear English writing. But should you write “five” or “5”? Is it better to write “twenty-one” or “21”? And what rules should you follow when writing dates, percentages, fractions, decimals, and large numbers?

Learning how to write numbers in English helps you avoid these common problems. The correct format often depends on the type of number, the context, and the style guide you are following.

In this guide, you’ll learn the basic rules for writing numbers in English, including when to spell out numbers and when to use numerals. You’ll also find clear examples covering cardinal numbers, ordinal numbers, large numbers, fractions, decimals, dates, times, percentages, money, and measurements.

Basic Rules for Writing Numbers in English

When writing numbers in English, you can either spell them out as words or write them as numerals. For example, you can write six as a word or 6 as a numeral.

The correct choice depends on the type of writing, the number being used, and the style guide you are following.

When to Spell Out Numbers

In general writing, small whole numbers are often written as words, especially in ordinary sentences.

Examples:

• She bought three books.

• We have two English classes today.

• He invited seven friends to the party.

• They stayed for five days.

However, different style guides have different rules. For example, some recommend spelling out numbers from one through nine, while others spell out whole numbers through one hundred in many situations.

For this reason, always follow the required style guide when writing an academic paper, professional document, or publication.

When to Use Numerals

Numerals are commonly used when numbers represent precise information, especially with measurements, statistics, dates, times, money, and percentages.

Examples:

• The meeting begins at 3:30 p.m.

• The box weighs 12 kg.

• Sales increased by 15%.

• The ticket costs $25.

• She was born in 1998.

• The temperature reached 30°C.

Numerals are also generally easier to read when dealing with large numbers.

Example:

• The stadium can hold 45,000 people.

This is usually easier to read than:

• The stadium can hold forty-five thousand people.

Numbers at the Beginning of a Sentence

As a general writing convention, avoid starting a sentence with a numeral. If a number appears at the beginning, spell it out.

Correct:

Twenty-five students attended the workshop.

Avoid:

25 students attended the workshop.

For very large or complicated numbers, rewriting the sentence is often better.

Instead of:

1,250 people attended the event.

Write:

The event attracted 1,250 people.

Be Consistent

Consistency is important when numbers appear together or perform the same function in a sentence, table, or list.

For example:

The class included 8 beginners, 12 intermediate students, and 15 advanced students.

Using the same number format makes the information easier to compare and understand.

How to Write Numbers in English

Numbers can be written as numerals or words. For example, the number 12 can be written as 12 or twelve. When writing numbers in words, you need to follow standard English spelling and punctuation rules.

Writing Numbers from 1 to 20

The numbers from 1 to 20 have their own spellings and are useful to learn individually.

Writing Numbers from 21 to 99

For numbers from 21 to 99 that are not exact multiples of ten, use a hyphen between the tens and ones.

Examples:

• 21 — twenty-one

• 32 — thirty-two

• 45 — forty-five

• 58 — fifty-eight

• 67 — sixty-seven

• 79 — seventy-nine

• 86 — eighty-six

• 99 — ninety-nine

Exact multiples of ten do not need a hyphen:

• 20 — twenty

• 30 — thirty

• 40 — forty

• 50 — fifty

• 60 — sixty

• 70 — seventy

• 80 — eighty

• 90 — ninety

Remember that forty is the correct spelling, not fourty.

Writing Hundreds in Words

Use hundred after the number that tells you how many hundreds there are.

Examples:

• 100 — one hundred

• 200 — two hundred

• 500 — five hundred

• 900 — nine hundred

For numbers between hundreds, combine the hundreds with the remaining number.

Examples:

• 125 — one hundred twenty-five

• 347 — three hundred forty-seven

• 682 — six hundred eighty-two

• 999 — nine hundred ninety-nine

In British English, and is commonly included after hundred:

• 125 — one hundred and twenty-five

• 347 — three hundred and forty-seven

Both patterns may be encountered, so learners should be aware of the difference between common American and British usage.

Writing Large Numbers

Large numbers are grouped into thousands, millions, billions, and beyond.

For example:

• 1,250 — one thousand two hundred fifty

• 25,000 — twenty-five thousand

• 150,000 — one hundred fifty thousand

• 2,500,000 — two million five hundred thousand

Commas make large numerals easier to read. In standard English-language formatting, commas commonly separate groups of three digits:

1,000 → 10,000 → 100,000 → 1,000,000

In many types of writing, very large round numbers can also be written using a combination of numerals and words.

Examples:

• 2 million people

• $5 billion

• 10 million users

Cardinal Numbers

Cardinal numbers tell us how many people or things there are.

Examples include:

• one

• two

• three

• ten

• twenty

• one hundred

In sentences:

• She has three brothers.

• We ordered six pizzas.

• The company employs 500 people.

Cardinal numbers answer the question “How many?”

Ordinal Numbers

Ordinal numbers show position or order rather than quantity.

Examples:

• She finished first in the competition.

• This is my second attempt.

• Their office is on the fifth floor.

• He celebrated his 21st birthday.

Ordinal numbers are commonly used for rankings, sequences, floors, anniversaries, and other forms of order.

Writing Fractions

Fractions can be written with numerals or words depending on the context.

Examples:

• 1/2 — one-half

• 1/3 — one-third

• 1/4 — one-fourth or one-quarter

• 2/3 — two-thirds

• 3/4 — three-fourths or three-quarters

When fractions are written as words, they are often hyphenated.

Examples:

• She ate one-half of the cake.

• Two-thirds of the students completed the assignment.

• Add three-quarters of a cup of milk.

Writing Decimals

Decimals are generally written using numerals.

Examples:

• 0.5

• 1.25

• 3.14

• 10.75

When reading decimals aloud, say point for the decimal point and usually read the digits after it individually.

For example:

• 0.5 — zero point five

• 1.25 — one point two five

• 3.14 — three point one four

• 10.75 — ten point seven five

A zero before the decimal point is generally helpful when the value is less than one because it makes the number easier to recognize.

Numbers in Different Contexts

The way you write numbers can change depending on the type of writing. Academic papers, business reports, technical documents, and informal messages do not always follow exactly the same conventions.

Numbers in Academic Writing

In academic writing, the most important rule is to follow the style guide required by your school, university, journal, or instructor.

Different academic style guides have different rules about when numbers should be spelled out and when numerals should be used. Therefore, avoid assuming that one rule applies to every academic paper.

Numerals are commonly used for information such as:

• statistics

• percentages

• measurements

• dates

• times

• ages

• scores

• mathematical data

Examples:

• The study included 75 participants.

• The experiment lasted 6 weeks.

• Approximately 45% of respondents selected the first option.

• The sample weighed 25 g.

• Data were collected in 2025.

When writing an academic paper, consistency is essential. Check the required style guide before deciding how to format numbers throughout your work.

Numbers in Professional and Business Writing

Business and professional writing often favors numerals because they allow readers to identify important figures quickly.

This is especially useful in reports, financial documents, presentations, emails, invoices, and other data-heavy documents.

Examples:

• Revenue increased by 12% this quarter.

• The project will cost approximately $25,000.

• We received 48 applications.

• The meeting begins at 10:30 a.m.

• The company hired 15 new employees.

When several figures are being compared, using numerals usually makes the information easier to scan.

For example:

Sales increased from $50,000 in January to $65,000 in February.

Numbers in Technical and Scientific Writing

Technical and scientific writing frequently uses numerals, particularly when numbers are combined with units of measurement.

Examples:

• 5 cm

• 12 kg

• 25°C

• 60 km/h

• 250 mL

Using numerals helps communicate measurements and technical information precisely.

However, formatting conventions can vary between disciplines and publications, so writers should follow the appropriate technical or scientific style guide when one is required.

Numbers in Informal Writing

Informal writing—including personal emails, text messages, and social media posts—usually allows more flexibility.

For example, you might write:

• I’ll be there in 10 minutes.

• We invited five friends.

• The movie starts at 8:00.

• I have two questions for you.

Both words and numerals may be appropriate depending on the sentence. The main goal is to make the message easy to read and understand.

Avoid using text-message abbreviations such as “2” for “to” or “4” for “for” in formal, academic, or professional writing.

Follow the Appropriate Style Guide

There is no single number-formatting rule that applies to every type of English writing.

If you are writing for school, work, or publication, check whether you are expected to follow a particular style guide, such as APA, MLA, Chicago, or another publication-specific guide.

If no style guide is required, choose a clear format and use it consistently throughout your writing.

Special Cases When Writing Numbers

Some types of numbers follow their own conventions. Dates, times, years, percentages, money, measurements, addresses, and phone numbers are usually written with numerals for clarity.

Writing Dates

Dates can be written in several ways depending on whether you are using American or British English.

American English:

• September 2, 2026

• July 4, 2026

British English:

• 2 September 2026

• 4 July 2026

When the month is written as a word, American English normally places the month before the day, while British English commonly places the day before the month.

Numeric dates can sometimes cause confusion. For example:

04/07/2026

could mean April 7, 2026 in a month-day-year system or 4 July 2026 in a day-month-year system.

For international communication, spelling out the month can make the date clearer.

Writing Years

Years are normally written with numerals.

Examples:

• 1995

• 2000

• 2026

In sentences:

• She graduated in 2019.

• The company was founded in 2005.

• The project will end in 2027.

Decades can also be written with numerals:

• the 1980s

• the 1990s

• the 2020s

Do not normally use an apostrophe before the s when referring to an entire decade.

Correct: the 1990s
Incorrect: the 1990’s

Writing Time

Times are usually written with numerals when an exact time is given.

Examples:

• 7:30 a.m.

• 10:15 p.m.

• 2:45

• 6:00

In less formal writing, times can also be expressed in words.

Examples:

• seven o’clock

• half past six

• a quarter past three

• a quarter to nine

The exact formatting of a.m. and p.m. can vary by style guide. You may also see AM/PM or am/pm. Whichever style you use, be consistent.

Writing Money and Currency

Money is generally written using numerals when an exact amount is important.

Examples:

• $5

• $25.50

• £100

• €75

You can also combine numerals with words for large amounts:

• $2 million

• £5 billion

• €10 million

In ordinary sentences, amounts may sometimes be written in words.

Example:

• She gave him five dollars.

In financial and business writing, numerals are usually easier to scan and compare.

Writing Percentages

Percentages are commonly written with numerals.

Examples:

• 5%

• 25%

• 50%

• 99%

In sentences:

• Sales increased by 15%.

• About 60% of the students passed the test.

• The company reduced its costs by 8%.

Whether to use the % symbol or spell out percent can depend on the style guide and type of writing.

For example:

• 25%

• 25 percent

Follow the required style guide and remain consistent throughout your document.

Writing Measurements

Numerals are generally used with units of measurement, particularly in scientific, technical, and professional writing.

Examples:

• 5 cm

• 10 kg

• 25 km

• 2 L

• 30°C

In sentences:

• The table is 2 meters long.

• The package weighs 5 kg.

• The temperature reached 30°C.

• We traveled approximately 150 km.

When writing measurements, use the appropriate unit and keep the formatting consistent.

Writing Ages

Ages are commonly written with numerals, especially when the exact age is important.

Examples:

• She is 25 years old.

• The program is designed for children aged 8 to 12.

• He started learning English at age 10.

When an age appears before a noun as a compound adjective, hyphens are normally used.

Example:

• She has a 10-year-old son.

Notice that year remains singular in the compound adjective.

Writing Addresses

Street numbers are normally written as numerals.

Examples:

• 25 Main Street

• 150 Park Avenue

• 742 Oak Road

Using numerals makes addresses easier to identify and prevents unnecessary ambiguity.

Writing Phone Numbers

Phone numbers should be written with numerals rather than words.

Examples:

• (123) 456-7890

• 123-456-7890

• +1 123 456 7890

Phone-number formats vary by country, so use the format appropriate for the region and audience.

Writing Numbers in Lists and Tables

Numerals are usually preferable in tables, charts, statistics, and lists containing numerical data because they are easier to compare.

For example:

Using numerals consistently makes numerical information easier for readers to scan and understand.

Common Mistakes When Writing Numbers in English

Even experienced writers sometimes make mistakes when writing numbers. Here are some of the most common errors and how to avoid them.

1. Spelling Numbers Incorrectly

Some English number words have spellings that are easy to confuse.

Incorrect: fourty
Correct: forty

Incorrect: ninty
Correct: ninety

Incorrect: fiveteen
Correct: fifteen

Incorrect: twelveth
Correct: twelfth

Pay special attention to irregular spellings such as forty, fifty, eighty, ninety, fifth, ninth, and twelfth.

2. Forgetting Hyphens in Compound Numbers

When numbers from 21 to 99 are written as words and are not exact multiples of ten, use a hyphen between the tens and ones.

Incorrect: twenty five
Correct: twenty-five

Incorrect: sixty seven
Correct: sixty-seven

Incorrect: ninety nine
Correct: ninety-nine

Exact multiples of ten do not need hyphens:

• twenty

• forty

• sixty

• ninety

3. Using a Numeral at the Beginning of a Sentence

In general prose, avoid beginning a sentence with a numeral.

Avoid:

25 students participated in the activity.

Better:

Twenty-five students participated in the activity.

For large or complicated numbers, rewriting the sentence is often easier.

Awkward:

1,275 people attended the event.

Better:

The event attracted 1,275 people.

4. Adding an Unnecessary Apostrophe to Decades

Do not normally use an apostrophe before the s when referring to a complete decade.

Incorrect: the 1990’s
Correct: the 1990s

Incorrect: the 2020’s
Correct: the 2020s

The s makes the decade plural; it does not indicate possession.

5. Confusing Cardinal and Ordinal Numbers

Cardinal numbers tell us how many, while ordinal numbers tell us position or order.

Cardinal:

• one

• two

• three

• twenty

Ordinal:

• first

• second

• third

• twentieth

For example:

Correct: She has three books.
Correct: She finished third in the race.

Do not use an ordinal number when you are describing quantity.

6. Using the Wrong Ordinal Ending

Ordinal abbreviations usually end in st, nd, rd, or th.

Examples include:

• 1st

• 2nd

• 3rd

• 4th

• 21st

• 22nd

• 23rd

• 24th

However, 11, 12, and 13 are exceptions:

Correct: 11th, 12th, 13th
Incorrect: 11st, 12nd, 13rd

7. Making “Hundred,” “Thousand,” or “Million” Plural After an Exact Number

When a specific number comes before hundred, thousand, million, or billion, these words normally remain singular.

Correct:

• two hundred students

• five thousand dollars

• three million people

Incorrect:

• two hundreds students

• five thousands dollars

• three millions people

However, the plural forms can be used when referring to an approximate quantity:

• hundreds of students

• thousands of people

• millions of dollars

8. Using Inconsistent Number Formats

Numbers performing similar functions should usually follow a consistent format, especially in lists, tables, reports, and data comparisons.

For example:

Clear and consistent:

The three groups contained 8, 12, and 15 participants.

Consistency makes numerical information easier to read and compare.

9. Confusing American and British Date Formats

Numeric dates can have different meanings in different countries.

For example:

05/09/2026

may be interpreted as May 9, 2026 in the United States but 5 September 2026 in countries that use the day-month-year format.

When writing for an international audience, spelling out the month can prevent confusion:

5 September 2026

or

September 5, 2026

10. Ignoring the Required Style Guide

One of the biggest mistakes is assuming that every type of writing follows exactly the same rules for numbers.

APA, MLA, Chicago, newspapers, academic journals, businesses, and other organizations may have different conventions.

Before submitting formal or academic work, check the required style guide and apply its number rules consistently.

Tips for Writing Numbers Correctly in English

Knowing the basic rules is important, but good number writing also depends on clarity, consistency, and context. These tips can help you decide how to write numbers in English more accurately.

1. Choose Words or Numerals Based on Context

Do not assume that every number must be written the same way. Consider what the number represents and where it appears.

Words often work well in ordinary prose:

• She bought three books.

• We waited for five days.

Numerals are often clearer for precise information:

• The temperature was 28°C.

• Sales increased by 12%.

• The meeting starts at 9:30 a.m.

The goal is to make the information easy for your reader to understand.

2. Be Consistent

Once you choose a number format for similar information, use it consistently.

For example:

Clear: The groups contained 8, 12, and 16 students.

Inconsistent formatting can make lists, statistics, and comparisons harder to read.

3. Use Numerals for Data-Heavy Content

Numerals are generally easier to scan in tables, charts, reports, statistics, and other content containing many numbers.

For example:

• January: 125 visitors

• February: 180 visitors

• March: 240 visitors

Writing these figures entirely in words would make the information more difficult to compare quickly.

4. Spell Out Numbers When It Improves Readability

In ordinary sentences, writing smaller numbers as words can make prose feel more natural.

For example:

She asked three questions during the lesson.

However, readability and style requirements should guide your decision rather than an inflexible rule.

5. Pay Attention to Number Spelling

Double-check number words that are commonly misspelled.

Remember:

• forty, not fourty

• fifty, not fivety

• eighty, not eightty

• ninety, not ninty

• twelfth, not twelveth

Correct spelling is especially important when numbers are written entirely in words.

6. Use Hyphens Correctly

Use hyphens in compound numbers from twenty-one through ninety-nine when they are written as words.

Examples:

• twenty-one

• thirty-five

• sixty-eight

• ninety-nine

The same principle appears in compound ordinal numbers:

• twenty-first

• thirty-second

• forty-third

• ninety-ninth

7. Make Large Numbers Easy to Read

Use appropriate grouping and formatting for large numerals.

For example:

1,500,000

is easier for many English-language readers to recognize quickly than:

1500000

For round figures, combining numerals and words can sometimes improve readability:

• 5 million

• $10 billion

• 2.5 million users

Choose the format that communicates the number most clearly.

8. Avoid Ambiguous Dates

If your writing may be read internationally, numeric dates can cause confusion.

Instead of:

06/08/2026

consider writing:

June 8, 2026

or:

8 June 2026

Writing the month as a word makes the date much clearer.

9. Follow the Required Style Guide

For academic, professional, or published writing, check whether a particular style guide is required.

APA, MLA, Chicago, individual publishers, universities, and organizations may use different conventions for numbers.

The required style guide should take priority over general number-writing advice.

10. Proofread All Numerical Information

Number errors can easily change the meaning of a sentence. Before publishing or submitting your work, check:

• spelling of number words

• decimal points

• commas

• percentages

• dates

• currency amounts

• measurements

• ordinal endings

• hyphenation

Pay particular attention to numbers in academic papers, reports, invoices, statistics, and other documents where accuracy is essential.

11. Practice Writing Numbers in Different Forms

A useful way to improve is to convert numerals into words and words back into numerals.

For example:

47 → forty-seven

one hundred twenty-five → 125

2,500 → two thousand five hundred

three-quarters → 3/4

Regular practice will help you recognize common number patterns and write them more confidently.

Conclusion

Mastering the rules of writing numbers in English is a valuable skill that enhances your communication. By following the guidelines and practicing consistently, you’ll be able to write numbers accurately and confidently in any context.

Additional Resources

For further guidance, consider consulting recommended style guides such as the APA, MLA, or Chicago Manual of Style. Online resources and practice tools can also help you improve your skills.

• Numbers in English
• Numbers 1 to 100: Learn How to Count in English
• Ordinal Numbers in English
• How to Read Numbers in English
• Basic and Important Math Symbols in English
• What Is Academic Writing?