Grammar Rules for Writing Numbers

Instructor: Charles Kinney, Jr.
The grammar rules for writing numbers can be confusing. In this lesson, we will look at rules, exceptions and different accepted styles. While the rules may sometimes seem contradictory, the most important thing is to be consistent.

Grammar Rules or Style?

There are many grammar rules for writing numbers and sometimes they seem to contradict each other. These contradictions are not rules but questions of writing style. Teachers, writing forums like newspapers and magazines, and even schools will use different styles as their rules. The most important rule for writing numbers is that no matter which rule you decide to use, consistency is the key!

Four measuring cups: Does each have 1 and 1/4 cup of sugar or one and one-fourth cup of sugar?
sugar

Writing Numbers Chart

Rules Examples
0 - 9 = write out the number zero, one, two, three, etc. - She has six cats.
10 - ? = numerical value (also known as Arabic numeral) 10, 11, 12, 13, etc. - It took him 25 minutes to get here.
Number at the beginning of a sentence = write out the number Sixty-four days ago, we met each other. If you don't want to write out a long number, reorder the sentence: We met each other 64 days ago.
Add a hyphen (-) when writing out compound numbers 21 - 99 sixty-four / twenty-two / fifty-five
Add a comma (,) three places from the right when using numerical large numbers 1,248,396 / 349,245 / 1,901
Year = numerical value (even at the beginning of a sentence) 2015 was a good financial year for the company. If it doesn't look right, reorder the sentence: The company had a good financial year in 2015.
Time = numerical value I am finished at 5:00 PM. Note: Some people use the written form of a number if they use o'clock: I am finished at five o'clock.
Shortened decades = apostrophe ( ' ) AND no apostrophe During the '80s, many people had big sweaters. Also: During the 80's, many people had big sweaters. Both are acceptable. This sentence is OK but strange: During the '80's, many people had big sweaters.
Long decades = no apostrophe I really like the music from the 1990s. Incorrect: I really like the music from the 1990's.

Exceptions to 0 - 9 Rule

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