Writing Numbers (Part One)

In this lesson and the lesson that follows, we’re going to cover when you should write out numbers as words (twenty) and when you should write numbers as numerals (20). 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. Always consult your company’s style guide if you are unsure whether to write a number as words or use numerals.

Numbers as Written Words


Write out numbers that are one or two words long:

Our company has four locations.


            I logged almost one hundred hours on that project.


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

Incorrect:       I heard that Jan spent two hundred twenty-five hours on the project.


Correct:          I heard that Jan spent 225 hours on the project.


Write out all numbers that begin a sentence:

Five thousand people attended the conference.


            Seventy percent is equivalent to a “C” grade.


            Three employees called in sick today.


Do not 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:          The convention had 135,000 people in attendance.

Write out people’s ages and simple fractions:

Rick’s daughter is nineteen. His son is twenty-one.


            Cats spend two-thirds of their lives sleeping.


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

Her 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. Unless you are working in a scientific or technical field, avoid using symbols and abbreviations in formal writing:

Correct Incorrect
Numbers as Words Numerals withSymbols Words with Symbols or Abbreviations
Fifty percent 50% Fifty %
Three hundred dollars $300 Three hundred $
Six feet two inches 6’2” Six’ two”6 ft, two in
Seventy pounds 70 lb Seventy lb
Twelve centimeters 12 cm Twelve cm