In the English language, there are rules to when you should write out numbers as words (twenty) and when you should write numbers as numerals (20). How do you know the difference? We’re going to look at some general guidelines now, but keep in mind that these rules might differ from the rules used in your workplace, especially if you work in a scientific or technical field.

Numbers as Written Words

Write out numbers that are one or two words long:

That franchise only has four locations.

 I logged almost one hundred hours on the quarterly project.

 

Use numerals for numbers that would be three or more words long:

Incorrect:       Freddy spent two hundred twenty-five hours on the presentation.  

Correct:          Freddy spent 225 hours on the presentation.

 

Write out all numbers that begin a sentence:

Five thousand people attended the mayor’s rally.

Eighty percent on an exam is usually considered a “B” grade.

Three employees called in sick yesterday.

 

Try not to start a sentence with a number consisting of three or more words. Rewrite the sentence instead:

Incorrect:       One hundred thirty-five thousand people attended the convention.

Correct:          Reports say that over 135,000 people attended the convention.

 

Write out people’s ages and simple fractions:

Kelly’s daughter is nineteen. Her son is almost twenty-one.

Cats spend two-thirds of their lives sleeping.

 

However, you should use numerals when a person’s age is over one hundred:

My grandmother lived to the age of 103.

 

Do not mix words and numerals when numbers are in a series:

Incorrect:       He owns 165 DVDs, seventy video games, and fifty-five books.

Correct:          He owns 165 DVDs, 70 video games, and 55 books.

 

When two numbers are together, write one number in words and the other number in numerals for clarity:

Susan bought a package of three $20 gift cards.

Ron worked 6 twelve-hour days to finish the project by the deadline.

 

For round numbers larger than one million, use a combination of numerals and words:

There are over 3.9 million people living in the state of Georgia.

The philanthropist donated $1.5 million of his own money to the relief effort.

 

Do not combine symbols or abbreviations and numbers as written words. Here are some examples of statistics and measurements commonly used with abbreviations:

Fifty Percent (50%)

Two hundred dollars ($200)

Twenty-five pounds (25 lbs)

Sixteen centimeters (16 cm)

As shown here, there are many ways you may need to write out numbers when learning English. If these rules are still confusing, or if you need help with vocabulary, grammar, or any other part of the English language, The English Island school in Atlanta teaches group and individual classes at all proficiency levels. Our dedicated teachers can help you master numbers and notation along with other subjects that are often difficult for ESL students.