when to spell out numbers in research paper

Numbers Expressed in Numerals

In general, use numerals to express numbers 10 and above, and use words to express numbers zero through nine .

there were 15 psychologists at the clinic

the study had 40 participants

students were in the third, sixth, eighth, 10th, and 12th grades

However, there are exceptions to this general guideline for number usage. There are cases in which you should always use numerals to express numbers, even numbers zero through nine, and likewise, there are cases in which you should always use words to express numbers, even numbers 10 and above.

Numbers expressed in numerals are covered in the seventh edition APA Style manuals in the Publication Manual 6.32 and the Concise Guide Section 6.1

Related handout

• Numbers and Statistics Guide (PDF, 122KB)

Cases in which to always use numerals for numbers

Always use numerals to express numbers in the following cases, even numbers zero through nine:

Numbers in a series

Also use numerals to write numbers that denote a specific place in a numbered series when the number comes after the noun (e.g., Step 1). The noun before the number is also capitalized. This guideline applies to parts of books and tables as well (e.g., Chapter 1).

However, when the number comes before the noun, the usual guidelines for number use apply, as in the following examples.

Exceptions : Do not capitalize the abbreviations for page(s) or paragraph(s), even when they are followed by a numeral (e.g., p. 3, pp. 2–5, para. 9, paras. 1–4).

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Although usage varies, most people spell out numbers that can be expressed in one or two words and use figures for numbers that are three or more words long. Note: If you are using a specific citation style, such as MLA or APA , consult the style manual for specific formatting instructions.

Here are some examples of specific situations:

Days and Years

Time of Day

Identification Numbers

Page and Division of Books and Plays

Decimals and Percentages

Large Round Numbers

Notes on Usage

Repeat numbers in commercial writing.

Use numerals in legal writing.

Numbers in series and statistics should be consistent.

Write out numbers beginning sentences.

Use a combination of figures and words for numbers when such a combination will keep your writing clear.

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Other APA Guidelines: Numbers

Basics of numbers.

Per APA 7, Section 6.32, use numerals to express numbers 10 or above (e.g., 11, 23, 256). Per Section 6.33, write out numbers as words to express numbers up to nine (e.g., three, seven, eight).

Take the APA Style Diagnostic Quiz  to test your knowledge.

Numbers Expressed as Words

Use words to express numbers in these situations:

Seventeen computer programmers went out to dinner last night

The principal presented awards to three fourths of the student body.

(This is a new rule in APA 7. APA 6 recommended using numerals in the abstract.)

Numbers Expressed as Numerals

Use numerals to express numbers in these situations:

She had been a nurse for 3 years.

Chapter 4 was considered required reading.

The student scored a perfect 7.

Each post was roughly 2.45 ft apart.

Teachers gave students ice cream if they scored in the top 5%.

You owe me $5.

Numbers Video

• APA Formatting & Style: Numbers (video transcript)

Related Resources

Knowledge Check: Numbers

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When to Spell Out Numbers in Writing: Guide and Examples

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The Rules for Writing Numbers in English 

You may have noticed a theme when it comes to the English language: most rules are not standardized. This (somewhat frustrating) fact is especially true when it comes to spelling out numbers. Should you write them out in words or leave them as numerals? To write numbers properly, you will also need to identify potential differences between major style guides (such as MLA , APA , and Chicago , to name a few) because these guides often outline different rules for using numbers in writing.

To make it easier, let's use an example. Say you're working on a paper evaluating the importance of the local public library in your community. The document will make use of small numbers, large numbers, decades, and statistics. Each type of number may follow a different rule.

Thankfully, when using numbers in writing, you can count on a few conventions that apply to most situations; just be sure to consult your specific style guide if one has been assigned. If you don't have time to review each number yourself, a professional editor or proofreader can ensure that your numbers are written correctly.

Writing Small and Large Numbers

A simple rule for using numbers in writing is that small numbers ranging from one to ten (or one to nine, depending on the style guide) should generally be spelled out. Larger numbers (i.e., above ten) are written as numerals.

For example, instead of writing "It cost ten-thousand four-hundred and sixteen dollars to renovate the local library," you would write, "It cost $10,416 to renovate the local library."

The reason for this is relatively intuitive. Writing out large numbers not only wastes space but could also be a major distraction to your readers.

Beginning a Sentence with a Number

Here is a rule that you can truly rely on: always spell out numbers when they begin a sentence, no matter how large or small they may be.

Incorrect: 15 new fiction novels were on display.

Correct: Fifteen new fiction novels were on display.

If the number is large and you want to avoid writing it all out, rearrange the sentence so that the number no longer comes first.

Revised: There were 15 new fiction novels on display.

Whole Numbers vs. Decimals

Another important factor to consider is whether you are working with a whole number or a decimal. Decimals are always written as numerals for clarity and accuracy.

To revisit our library example, perhaps circulation statistics improved in 2015. If a number falls in the range of one to ten and is not a whole number, it should be written as a numeral.

Incorrect: The circulation of library materials increased by four point five percent in 2015.

Correct: The circulation of library materials increased by 4.5% in 2015.

Paired Numbers (Two Numbers in a Row)

When two numbers come next to each other in a sentence, be sure to spell out one of these numbers. The main purpose of this rule is to avoid confusing the reader.

Incorrect: There were 12 4-year-old children waiting for the librarian to begin story time.

Correct: There were 12 four-year-old children waiting for the librarian to begin story time.

Correct: There were twelve 4-year-old children waiting for the librarian to begin story time.

Decades and Centuries

Decades or centuries are usually spelled out, especially if the writing is formal.

Incorrect: The library was built in the '50s.

Correct: The library was built in the fifties.

If you are referring to a specific year (e.g., 1955), use the numeral.

Consistency Is Key When Using Numbers in Your Writing

Always strive for consistency, even if it overrides a previous rule. For example, if your document uses numbers frequently, it is more appropriate for all numbers to remain as numerals to ensure that usage is uniform throughout. Similarly, if a single sentence combines small and large numbers, make sure that all the numbers are either spelled out or written as numerals.

Incorrect: The library acquired five new mystery novels, 12 new desktop computers, and 17 new periodicals.

Correct: The library acquired 5 new mystery novels, 12 new desktop computers, and 17 new periodicals.

Style Guides May Have Slightly Different Rules for Writing Numbers in Words

Let's complicate things a bit, shall we?

If your work must follow the rules of a specific style guide, understand that various guides all have rules for spelling out numbers that may differ slightly from the rules listed above. For example, MLA style indicates that writers may spell out numbers if they are not used too frequently in the document and can be represented with one or two words (e.g., twenty-four, one hundred, three thousand ). APA style advises that common fractions (e.g., two-thirds ) be expressed as words. A number of specific rules for spelling out numbers are outlined in Section 9.1 of the Chicago Manual of Style.

Your ultimate authority will always be a style guide, but in the absence of one, following the rules outlined above will help you stay consistent in your use of numbers in writing.

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• APA Style 7th edition
• Reporting Statistics in APA Style | Guidelines & Examples

Reporting Statistics in APA Style | Guidelines & Examples

Published on April 1, 2021 by Pritha Bhandari . Revised on January 17, 2024.

The APA Publication Manual is commonly used for reporting research results in the social and natural sciences. This article walks you through APA Style standards for reporting statistics in academic writing.

Statistical analysis involves gathering and testing quantitative data to make inferences about the world. A statistic is any number that describes a sample : it can be a proportion, a range , or a measurement, among other things.

When reporting statistics, use these formatting rules and suggestions from APA where relevant.

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Table of contents

Numbers and measurements, decimal places and leading zeros, formatting mathematical formulas, formatting statistical terms, reporting means and standard deviations, reporting chi-square tests, reporting z tests and t tests, reporting analysis of variance (anovas), reporting correlations, reporting regressions, reporting confidence intervals, other interesting articles, frequently asked questions about apa style statistics.

In general, APA advises using words for numbers under 10 and numerals for 10 and greater . However, always spell out a number that appears at the start of a sentence (or rephrase).

You should always use numerals for:

• Exact numbers before units of measurement or time
• Mathematical equations
• Percentages and percentiles
• Ratios, decimals, and uncommon fractions
• Scores and points on scales (e.g., 7-point scale)
• Exact amounts of money

Units of measurement and time

Report exact measurements using numerals, and use symbols or abbreviations for common units of measurement when they accompany exact measurements. Include a space between the number and the abbreviation.

When stating approximate figures, use words to express numbers under 10, and spell out the names of units of measurement.

• The ball weighed 7 kg.
• The ball weighed approximately seven kilograms.

Measurements should be reported in metric units. If you recorded measurements in non-metric units, include metric equivalents in your report as well as the original units.

Percentages

Use numerals for percentages along with the percent symbol (%). Don’t insert a space between the number and the symbol.

Words for “percent” or “percentage” should only be used in text when numbers aren’t used, or when a percentage appears at the start of a sentence.

• Of these respondents, 15% agreed with the statement.
• Fifteen percent of respondents agreed with the statement.
• The percentage was higher in 2020.

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The number of decimal places to report depends on what you’re reporting. Generally, you should aim to round numbers while retaining precision. It’s best to present fewer decimal digits to aid easy understanding.

The following guidelines are usually applicable.

Use two or three decimal places and report exact values for all p values greater than .001. For p values smaller than .001, report them as p < .001.

Leading zeros

A leading zero is zero before the decimal point for numbers less than one. In APA Style, it’s only used in some cases.

Use a leading zero only when the statistic you’re describing can be greater than one. If it can never exceed one, omit the leading zero.

• Consumers reported high satisfaction with the services ( M = 4.1, SD = 0.8).
• The correlation was medium-sized ( r = .35).
• Although significant results were obtained, the effect was relatively small ( p = .015, d = 0.11).

Provide formulas only when you use new or uncommon equations. For short equations, present them within one line in the main text whenever possible.

Make the order of operations as clear as possible by using parentheses (round brackets) for the first step, brackets [square brackets] for the second step, and braces {curly brackets} for the third step, where necessary.

More complex equations, or equations that take more than one line, should be displayed on their own lines. Equations should be displayed and numbered if you will reference them later on, regardless of their complexity. Number equations by placing the numbers in parentheses near the right edge of the page.

When reporting statistical results , present information in easily understandable ways. You can use a mix of text, tables, and figures to present data effectively when you have a lot of numbers to report.

In your main text, use helpful words like “respectively” or “in order”  to aid understanding when listing several statistics in a sequence.

The APA manual provides guidelines for dealing with statistical terms, symbols and abbreviations.

Symbols and abbreviations

Population parameters are often represented with Greek letters, while sample statistics are often represented with italicized Latin letters.

Use the population symbol ( N ) for the total number of elements in a sample, and use the sample symbol ( n ) for the number of elements in each subgroup of the full sample.

In general, abbreviations should be defined on first use, but this isn’t always the case for common statistical abbreviations.

Capitalization, italicization and hyphenation

Statistical terms such as t test, z test, and p value always begin with a lowercase, italicized letter. Never begin a sentence with lowercase statistical abbreviations.

These statistical terms should only be hyphenated when they modify a subsequent word (e.g., “ z -test results” versus results of “ z tests”).

You can form plurals of statistical symbols (e.g., M or p ) by adding a non-italicized “s” to the end with no apostrophe (e.g., M s or p s).

In general, the following guidelines apply.

Parentheses vs. brackets

Always aim to avoid nested parentheses and brackets when reporting statistics. Instead, you should use commas to separate related statistics.

• Scores improved between the pretest and posttest ( p < .001).
• Significant differences in test scores were recorded, F (1, 30) = 4.67, p = .003.
• (A previous meta-analysis highlighted low effect sizes [ d = 0.1] in the field).

Report descriptive statistics to summarize your data. Quantitative data is often reported using means and standard deviations, while categorical data (e.g., demographic variables) is reported using proportions.

Means and standard deviations can be presented in the main text and/or in parentheses. You don’t need to repeat the units of measurement (e.g., centimeters) for statistics relating to the same data.

• Average sample height was 136.4 cm ( SD = 15.1).
• The height of the initial sample was relatively low ( M = 125.9 cm, SD = 16.6).
• Height significantly varied between children aged 5–7, 8–10, and 11–13. The means were 115.3, 133.5, and 149.1 cm, respectively.

To report the results of a chi-square test , include the following:

• the degrees of freedom ( df ) in parentheses
• the chi-square (Χ 2 ) value (also referred to as the chi-square test statistic)
• the p value
• A chi-square test of independence revealed a significant association between gender and product preference, Χ 2 (8) = 19.7, p = .012.
• Based on a chi-square test of goodness of fit , Χ 2 (4) = 11.34, p = .023, the sample’s distribution of religious affiliations matched that of the population’s.

For z tests

To report the results of a z test, include the following:

• the z value (also referred to as the z statistic or z score)
• The participants’ scores were higher than the population average, z = 2.48, p = .013.
• Higher scores were obtained on the new 20-item scale compared to the previous 40-item scale, z = 2.67, p = .007.

For t tests

To report the results of a t test , include the following:

• the t value (also referred to as the t statistic)
• Older adults experienced significantly more loneliness than younger adults, t (32) = 2.94, p = .006.
• Reaction times were significantly faster for mice in the experimental condition, t (53) = 5.94, p < .001.

To report the results of an ANOVA , include the following:

• the degrees of freedom (between groups, within groups) in parentheses
• the F value (also referred to as the F statistic)
• A one-way ANOVA demonstrated that the effect of leadership style was significant for employee engagement, F (2, 78) = 4.58, p = .013.
• We found a statistically significant main effect of age group on social media use, F (3, 117) = 3.19, p = .026.

To report the results of a correlation, include the following:

• the degrees of freedom in parentheses
• the r value (the correlation coefficient)
• We found a strong correlation between average temperature and new daily cases of COVID-19, r (357) = .42, p < .001.

Results of regression analyses are often displayed in a table because the output includes many numbers.

To report the results of a regression analysis in the text, include the following:

• the R 2 value (the coefficient of determination)

The format is usually:

• SAT scores predicted college GPA, R 2 = .34, F (1, 416) = 6.71, p = .009.

You should report confidence intervals of effect sizes (e.g., Cohen’s d ) or point estimates where relevant.

To report a confidence interval, state the confidence level and use brackets to enclose the lower and upper limits of the confidence interval, separated by a comma.

• Older adults experienced significantly more loneliness than younger adults, t (32) = 2.94, p = .006, d = 0.81, 95% CI [0.6, 1.02].
• On average, the treatment resulted in a 30% reduction in migraine frequency, 99% CI [26.5, 33.5].

When presenting multiple confidence intervals with the same confidence levels in a sequence, don’t repeat the confidence level or the word “CI.”

If you want to know more about statistics , methodology , or research bias , make sure to check out some of our other articles with explanations and examples.

• Chi square test of independence
• Statistical power
• Descriptive statistics
• Degrees of freedom
• Pearson correlation
• Null hypothesis

Methodology

• Double-blind study
• Case-control study
• Research ethics
• Data collection
• Hypothesis testing
• Structured interviews

Research bias

• Hawthorne effect
• Unconscious bias
• Recall bias
• Halo effect
• Self-serving bias
• Information bias

According to the APA guidelines, you should report enough detail on inferential statistics so that your readers understand your analyses.

Report the following for each hypothesis test:

• the test statistic value
• the degrees of freedom
• the exact p value (unless it is less than 0.001)
• the magnitude and direction of the effect

You should also present confidence intervals and estimates of effect sizes where relevant.

Use one decimal place for:

• Standard deviations
• Descriptive statistics based on discrete data

Use two decimal places for:

• Correlation coefficients
• Proportions
• Inferential test statistics such as t values, F values, and chi-squares.

In APA style, statistics can be presented in the main text or as tables or figures . To decide how to present numbers, you can follow APA guidelines:

• To present three or fewer numbers, try a sentence,
• To present between 4 and 20 numbers, try a table,
• To present more than 20 numbers, try a figure.

Since these are general guidelines, use your own judgment and feedback from others for effective presentation of numbers.

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When to spell out numbers in scientific writing

• by kayciebutler
• August 3, 2021 August 3, 2021

When to spell out numbers in scientific writing can be tricky, and how/when to do this is one of the most common questions I get. And I get it…sometimes they are numerals and sometimes they are spelled out, and this can seem both arbitrary and not worth your time to figure out.

If you are anything like I was when writing, sometimes you just have more important things to worry about than stressing over what seems like trivial details – like if your numbers should be spelled out or written as numerals.

Numbers are one of those parts of scientific writing that, when done correctly, blend seamlessly into the overall document and lead to this assumption that they are just a trivial detail.

Unfortunately, incorrectly written numbers can make your paper difficult to understand and can even lead a reader astray when interpreting your science.

Luckily, the rules for writing numbers are actually quite specific and not so tough once you know what to watch out for.

And here they are, all in one place for your writing needs! Enjoy!

Skip to your scenario

Or straight to the INFOGRAPHIC!

• Except: Figures and tables
• Except: Dates and times
• Except: Statistics and counting
• Mixed numbers – numbers below and above 10 in the same sentence
• Except: At the beginning of a sentence
• Writing a number with a unit
• Two numbers in a row

To learn how to spell out numbers in a video

Most common situations for when to spell out numbers, –>zero-nine – generally spell out.

In general, the numbers zero-nine are spelled out when written in a sentence.

“The experiment was repeated five times.”

NOT: “The experiment was repeated 5 times.”

*Exception – Figures/Tables

Figure, table, and equation numbers should always be Arabic numerals.

Figure 1 , Table 2 , Equation 3

Not: Figure One , Table Two , Equation Three

Dates and times should always be Arabic numerals.

July 4, 1995, 4 July 1995, 10 p.m.

*Exception – statistics/counting

For statistics or counting purposes, the digits 0-9 can be written numerically.

“W e detected the protein in 9 of the 10 tested samples.”

“There were 5 participants in the study.”

->10, 11, 12 and higher – generally numerical

In general, numbers 10 and higher are written numerically.

“There were 15 participants in the study.”

NOT: “There were fifteen participants in the study.”

->Retaining consistency within a sentence

When multiple numbers are in the same sentence, it is easier to read if they are either all spelled out or all written numerically.

“The final results showed that 2 patients had no visible benefit from the treatment, 8 patients experienced some tumor shrinkage, and 12 patients experienced complete tumor regression.”

“The final results showed that two patients had no visible benefit from the treatment, eight patients experienced some tumor shrinkage, and twelve patients experienced complete tumor regression.”

Not: “The final results showed that two patients had no visible benefit from the treatment, eight patients experienced some tumor shrinkage, and 12 patients experienced complete tumor regression.”

->Beginning a sentence with a number – always spell out

Any number that starts a sentence should be spelled out, no matter the number.

“ Twenty participants returned for the follow-up study.”

Not: “ 20   participants returned for the follow-up study.”

“ Two thousand, two hundred and ninety six participants returned for the follow-up study.”

NOT: “ 2,296 participants returned for the follow-up study.”

However, writing out numbers at the start of a sentence can get a bit ugly, as seen from the last example above. There are several ways to handle this:

• Add the number in parentheses

“ Two thousand, two hundred and ninety six (2,296) participants returned for the follow-up study.”

• Rearrange the sentence to avoid

“For the follow-up study, 2,296 participants returned, and their progress was measured.”

*Exception – chemical names

The one exception is for chemical compounds with a number in their name. Always write this numerically, even when it starts a sentence.

“ 4 -methacryloxy-2-hydroxybenzophenone was the best-performing monomer.”

HOWEVER, I generally suggest ALL sentences starting with a number we reworded to avoid this entirely:

“We found that 4 -methacryloxy-2-hydroxybenzophenone was the best-performing monomer.”

->Writing amounts with a unit

The general rules on spelling out numbers zero-nine do not apply when writing a number attached to abbreviated units, generally in materials/methods sections.

The number should match the unit – if the unit is written out, the number should be written out. If the unit is abbreviated, the number should be abbreviated.

For example, all of the following are correct:

5 hrs, 5 mL, 5 °C, 5 %

five hours, five milliliters, five degrees Celsius, five percent

And you would not want to write

five hrs, five mL, five °C, five %

Uncommon Situations for when to spell out numbers

->two numbers in a row.

When two numbers appear back-to-back, there are two options:

• Spell out the number that is easiest to spell

NOT: “There were 12 100 -mL samples.”

“There were twelve 100 -mL samples.”

• Rearrange the sentence to avoid the problem

“ There were 12 samples of 100 mL each.”

->Fractions

In writing text, fractions should be spelled out, unless an exact quantity has to be conveyed:

• In written text

“ Two-thirds of the patients…”

• To convey an exact quantity

“The results showed that 17/58 samples tested positive.”

Infographic – When to spell out numbers in scientific writing

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Q. I often check dates and times for accuracy and have come across this question multiple times. If it is midnight, does that time belong to the day that is ending or the day that is beginning? For example, if it is 11:59 p.m. on April 12, and then it turns to be 12:00 a.m., should that 12:00 a.m. be noted as being on April 12? or April 13? I’ve seen it done both ways. Thanks!

A. You’re right: We can’t really know what day 12:00 a.m. refers to. So unless it’s clear from context, it’s best to specify both, as in 12:00 a.m., April 12–13—or, better yet, midnight, April 12–13. Because even though 12:00 a.m. is usually understood to mean midnight and 12:00 p.m. noon, both of those expressions are potentially ambiguous, at least outside of calendar apps and the like (see CMOS 9.40 ).

The twenty-four-hour system has a slight advantage here, but you still need two separate numbers. In that system, midnight on April 12 would be expressed as 2400 hours, whereas the beginning of April 13 would be 0000 hours. Those times are identical, but the numbers used to express them—and the dates they refer to—are different. See also CMOS 9.41 .

[This answer relies on the 18th edition of CMOS (2024) unless otherwise noted.]

Q. Which is the most correct phone number formatting—(xxx) xxx-xxxx, xxx-xxx-xxxx, or xxx.xxx.xxxx? Which is the most accessible?

A. You’ve punctuated your hypothetical telephone numbers—which are in the form most often used in the United States and Canada—in order of most familiar, most straightforward, and least conventional.

Putting the area code in parentheses is supposed to suggest that dialing it is optional. As area codes have increasingly become necessary even for local calls, this convention has nonetheless remained common.

As for accessibility, in our brief tests (using numerals rather than x ’s), all three formats were read as phone numbers by both Microsoft Word’s Read Aloud feature and Microsoft’s Narrator—that is, as a series of ten individual digits with a pause after the third and sixth and not as three large numbers, two of them in the hundreds and one of them in the thousands. And each was automatically turned into a callable phone number link in various messaging and email apps on a smartphone.

But only the first two are mentioned in the recommendations published by the International Telecommunication Union, so we’d advise using one of those (the ones without periods). See also CMOS 9.57 .

[This answer relies on the 17th edition of CMOS (2017) unless otherwise noted.]

Q. I’m finishing a book manuscript that includes uncommon fractions (such as 1/72) for which there aren’t single Unicode characters. How should I render my fractions? Using superscript for the numerator and subscript for the denominator results in inconsistent spacing. Even the existing Unicode fractions aren’t consistently kerned. Is there a way to have uniform-looking fractions regardless of the specific numbers? Thanks for your help.

A. You’re right that a single-character Unicode fraction like ½ (U+00BD, vulgar fraction one half) won’t match a fraction like 1/72 that relies on the forward slash (or solidus) character. One approach that can work in HTML (which is what you’re viewing right now) is to use a fraction slash (U+2044) instead of an ordinary forward slash (U+002F, the character that shares a key with the question mark on English-language QWERTY keyboards).

Unlike the forward slash, the fraction slash is designed to kern tightly to any character immediately before or after it. Best of all, the numbers before and after the slash will automatically go into fraction mode, adjusting their size and position relative to the slash (though not in all fonts):

Fraction slash, no superscripts or subscripts: 1⁄2 and 2⁄3 and 3⁄4 and 5⁄8 and 3⁄16 and 1⁄72

Forward slash (solidus), with superscripts and subscripts: 1 / 2 and 2 / 3 and 3 / 4 and 5 / 8 and 3 / 16 and 1 / 72

Both versions have a certain consistency to them, but the first set of fractions is better at matching the look of Unicode’s vulgar fractions. And according to the applicable Unicode chart (in what Unicode defines in its Help pages as an “informative note”), the fraction slash is intended “for composing arbitrary fractions”—which is the goal in this case.

But this approach won’t automatically work across applications. In a book manuscript composed in Word, you should probably use ordinary numbers with the forward slash—as in “1/72”—and ask your publisher or typesetter to format the fractions for you (e.g., using the available tools in a program like InDesign), specifying that you want them all to look like Unicode’s ½.

Q. Would you spell out 150,000?

A. Use numerals for 150,000. The applicable principles are as follows:

• Spell out numbers one through one hundred (Chicago’s general rule).
• Spell out multiples of one through one hundred used in combination with hundred , thousand , or hundred thousand .

So you would spell out “five thousand” and “one hundred thousand” but use digits for 150,000—because 150 would normally be rendered as a numeral.

But if you’re following Chicago’s alternative rule of using digits for 10 and up, all such larger numbers are usually given as numerals. Rather than, for example, “fifteen thousand” or “15 thousand,” you’d write 15,000.

For more details, see CMOS 9.2 , 9.3 , and 9.4 . For numbers with million , billion , and so forth, see CMOS 9.8 .

Q. I am editing an article that has sports terminology in it, and I wanted to verify whether a player’s jersey number would fall under the general rule of numbers or would be a special case in which the jersey number would be written as a numeral. And if it is to be written as a numeral, would an octothorpe/hashtag be used (for example, #24)?

A. Jersey numbers (like page numbers and a few other categories) are best expressed as numerals to reflect the way they normally appear in real life: Upon his much-anticipated return to the court, he wore number 45. * Usually, the word “number” can be spelled out; if you need to abbreviate it, we’d recommend using “No.”† instead of the number sign‡ (i.e., No. 45).

* Hint: The year was 1995, when CMOS was in its fourteenth edition.

† For the capital N , see this Q&A on a related matter (the No. 2 pencil) .

‡ “Number sign” is Unicode’s name for # (U+0023); the code chart for that symbol also lists pound sign , hashtag , hash , crosshatch , and octothorpe as what it calls informative aliases (which are preceded by equals signs in the charts; see “Key to the Unicode Code Charts” at Unicode’s Help and Links page).

Q. Sorry if I’ve overlooked a CMOS (or Q&A) answer to this question. I’m reviewing an organization’s bylaws, which contain several instances of a number spelled out followed by the number as a numeral in parentheses: e.g., “two (2).” I think parenthetical numerals are pointless redundancies. Does CMOS have a rule or preference related to this?

A. CMOS doesn’t cover this, but we agree with you, as does legal scholar and grammarian Bryan Garner: “The repetition of numbers by spelling them out and then using numerals typifies legalese and should never be used outside legal drafting. . . . Even in modern legal documents it’s largely uncalled for—the convention harks back to the days of legal scribes, who doubled words and numerals to prevent fraudulent alterations (words controlled over numerals).” See Garner’s Modern English Usage (Oxford, 2022), under “Numerals (G).”

Garner’s parenthetical observation that “words controlled over numerals” is interesting. In “two (3),” for example, the mistake would almost certainly be with the 3 and not the two (it’s easy to press a 1 or a 3 when a 2 is intended). That parenthetical numeral is subject not only to “fraudulent alterations” but to typos.

Q. When referring to the number of points possible on an exam, should I style numbers according to CMOS ’s general rule, or should I use numerals even for numbers below 101? Using numerals seems more common, but I’d like to know whether CMOS has an opinion.

A. There are many categories where numerals are generally used instead of words, from page numbers to sports scores. Whenever you suspect numerals would be more appropriate in a given scenario, particularly when referring to a type of number that would normally be expressed as a numeral in the wild (as page numbers on the pages of a book, scores on a scoreboard—or points tallied on an exam), then use numerals, even for numbers under 101.

Q. Hi. How do you write out grade levels? For example, would it be “third grade” or “3rd grade”? “Grade three” or “grade 3”? I cannot find the answer in CMOS 17; did I miss it? Thanks in advance!

A. Write “third grade” and “grade 3.” In Chicago style, the numbers zero through one hundred ( CMOS 9.2 ) or, alternatively, zero through nine ( 9.3 ) are spelled out. This applies whether the number is a cardinal (“one”) or an ordinal (“first”). But numerals are preferred in many expressions where the number follows the noun. For example, we’d refer to page 3, act 7, room 9, and Highway 2. Examples like these appear throughout CMOS , but none with grade levels. We’ll try to add some in a future edition.

Q. I understand a space is necessary between a number and a fraction when the fraction symbol is unavailable (e.g., 2 1/2), because the number would be illegible without it. But what if you use the symbol?

A. Fractional quantities expressed as a numeral plus a symbol are normally written without a space, as in 2½ or 5⅞. See CMOS 9.15 for examples.

Whether the symbol is used or not, these are known as “vulgar” fractions. For example, the Unicode name for “⅞” is “vulgar fraction seven eighths.” In this context, “vulgar” means “common.” We can only guess, then, that decimal fractions (e.g., 0.875) would be considered fancy by comparison.

Q. I’m editing a book that follows Chicago’s general rule for spelling out numbers zero through one hundred. In the construction “on a scale of 1 to 10,” would you spell out the numbers or use numerals? Thanks!

A. According to Google’s Ngram Viewer, numerals have been consistently more common in that expression in published books— but only slightly .

Would “1 to 10” be even more popular if CMOS 9.2 didn’t advise spelling out numbers one through one hundred in most contexts? Maybe.

But you can take this answer as permission to use numerals, which seem to do a better job than spelled-out numbers at suggesting the hypothetical scale in that expression.

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Using Numbers in Scientific Manuscripts

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When should you spell out a number in a scientific paper, and when do you use a numeral? Here's how to follow conventions and be consistent.

Updated on January 8, 2013

Writing a scholarly manuscript often requires the use of numbers to express important information, particularly in the sciences. Although the use of numbers is largely straightforward, there are a few things to keep in mind. In this article, numeral refers specifically to a number as it is written in mathematics (e.g., 4).

Do not start a sentence with a numeral

When writing for publication, try to use spelled-out numbers at the beginning of a sentence in place of numerals. This distinction is not based on grammar, but rather the conventions of academic writing in English.

• " 15 samples were collected " should be written as " Fifteen samples were collected "
• At times, writing out the numeral at the beginning of the sentence would be particularly unwieldy. In such cases, it is preferable to rearrange the sentence such that the numeral is not placed at the beginning. For example, " 6579 patient charts were collected for analysis " could be altered to " Charts from 6579 patients were collected for analysis "
• Note that some chemical compounds include numerals, and these should not be written out, even at the beginning of a sentence: " 5 -hydroxytryptamine is a neurotransmitter derived from tryptophan. "

Be consistent in the use of numerals or spelled-out numbers

Other tips for number usage involve consistency within your manuscript. As shown above, each number can be written as a numeral or a word. Many authors choose to use numerals for large numbers (say, those over 10) but words for small numbers. Either form is typically fine, but it is best to be consistent with your choice.

• If " We collected a total of eight samples " is written in your Methods section, avoid writing " Samples from all 8 lakes were nearly identical in pH " in your Results. Either correct the first sentence to include a numeral ('8') or change the second to the spelled-out word 'eight.'
• In addition, try to avoid mixing numerals and spelled-out words within a single sentence. For example, we suggest changing " The zoo has two pandas, eight elephants, and 15 orangutans " to " The zoo has two pandas, eight elephants, and fifteen orangutans ."

Other tips for consistency with numerals

Here are two other ways to make sure that your numerals are consistent within your manuscript. Consistency in your formatting choices is one way to demonstrate your attention to detail. Always consult your target journal's style sheet to see what they prefer.

• When using numbers larger than 1000, be sure to format them all in the same way. For example, 156000 , 156,000 , and 156 000 are all acceptable, but use only one format in your document.
• Be consistent with the inclusion or omission of a leading zero before decimals (i.e., 0.05 or .05 , but not both). Also, do not mix the use of a decimal point (0.12) with a decimal comma (0,12). In the vast majority of cases, journals prefer the use of the decimal point.

We hope that this article provides some guidance for the use of numbers in your writing. If you have specific questions about the numbers in your text, write to us by email at [email protected] . As always, AJE wishes you the best of luck with your research and publication!

Ben Mudrak, PhD

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Numbers in Scientific Manuscripts: What Are the Rules?

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Numbers in Writing: Guidelines for Life Sciences and Medicine (Part 3)

We hope that by now you are familiar with number conventions in formal writing. You can refer to Part 1 and Part 2 in this series, for a quick recap.

In this post, we will provide a simple rule of thumb and some exceptions for our biomedical authors.

While the style of literary texts is to spell out most numbers, that of scientific text is to use numerals when a degree of accuracy is intended. The modern scientific number style treats numbers more consistently by extending the use of “numerals” to most 1-digit whole numbers (1 to 9) that were previously expressed as words (one to nine). This style allows all quantities to be expressed in a similar manner. In addition, numerals have greater visual distinctiveness than words; it increases the profile of quantities in running text.

This article covers guidelines on scientific number style as recommended by the two predominant style guides in life sciences and medicine:

• Scientific Style and Format: The CSE Manual for Authors, Editors, and Publishers ( CSE )
• American Medical Association Manual of Style: A Guide for Authors and Editors ( AMA )

In actual application of these guidelines, however, when common sense or editorial judgment says a guideline is a poor choice for a specific document, follow sense or judgment.

Rule of Thumb

In a scientific text, Arabic numerals should be used in preference to words when the number designates anything that can be counted or measured.

For example,

• The authors detected VEGF in 12 of 12 samples from patients with NVG.
• We started the experiment with just 5 books (see Figure 1).

The rest of this article discusses six exceptions to this rule.

Exception 1: Beginning a Sentence, Title, Heading

Numerals are not used to begin a sentence, title, or heading. If logic calls for a number to begin a sentence, title, or heading, then spell out the number. If possible, reword so that the number appears elsewhere or connect the sentence to the previous or next sentence.

• Avoid: 35 cm is the preferred minimum operational snow base. However, ski areas in the study region produced a thicker snow base (usually 50−75 cm) early in the ski season.
• Spell out: Thirty-five centimeters is the preferred minimum operational snow base. However, ski areas in the study region produced a thicker snow base (usually 50−75 cm) early in the ski season.
• Reword: Although 35 cm is the preferred minimum operational snow base, ski areas in the study region produced a thicker snow base (usually 50−75 cm) early in the ski season.

Related: Need instant academic writing tips on your cell phone? Download the FREE Enago Academy mobile app now!

Spelling Tip!

When spelling out numerals, hyphenate numbers from twenty-one through ninety-nine when these numbers occur alone or as part of a larger number. When numbers greater than 100 are spelled out, do not use commas or “and” (e.g., one hundred forty-four).

Exception 2: Adjacent Numbers

When two numbers are adjacent, spell out the number most easily expressed in words and leave the other as a numeral, or reword the sentence to separate the numbers. In general, retain the numeral that occurs with a unit of measurement.

• Avoid: The fat content of the lesions could be identified on 3 10-mm sections.
• Spell out: The fat content of the lesions could be identified on three 10-mm sections.
• Reword: The fat content of the lesions could be identified on three sections of 10 mm each.

Exception 3: Zero (0) and One (1)

For these numbers, applying consistent logic (numerals for quantities and words otherwise) may make decisions about correct usage more difficult as they are also used in ways that are more like figures of speech than precise quantifications (“in one of the subjects…,” “zero-point energies”).

Express the whole numbers zero and one as numerals only when:

• they are connected to a unit of measure (1 year, 1 mm, 0 A, etc.)
• they are used as assigned or calculated values (when z = 0, a mean of 1)
• are part of a series or are closely linked with numbers other than 0 or 1 (0, 1, 5, and 9 were…, between 0 and 2)

Otherwise, spell out zero and one:

• …compared to the standard one (one used as a pronoun)
• one of the doctors (when “one” can be replaced with “a” or “a single”)
• on the one hand (transition phrase)
• zero-based budgeting (terms)
• one of whom could have been the leader (when emphasis on the quantity (0 or 1) would be confusing)

Exception 4: Accepted Usage/Idiomatic Expressions

When a number is used idiomatically or within a figure of speech, spell out the word; however, like jargon, figures of speech may be inappropriate for scientifically oriented writing because they may not be readily understood by readers whose first language is not English. Recasting the phrase is generally the better option.

• Avoid: We logged his sessions to learn a thing or 2, and warn his subsequent targets.
• Spell out: We logged his sessions to learn a thing or two, and warn his subsequent targets.
• Reword: We logged his sessions to learn some moves, and warn his subsequent targets.

Exception 5: Ordinal Numbers

In general, spell out single-digit ordinals (corresponding to the numbers 1 to 9), whether adjectives or adverbs.

• for the ninth time but for a 10th time
• were first discovered
• the third test run but the 98th test run

When there is a mix of single-digit and larger ordinals and double-digit ordinals, the express single-digit ordinals in the numeric form:

• Avoid: These correspond to daily values between the first and 15th of August 2003.
• Numeric Form: These correspond to daily values between the 1st and 15th of August 2003.

Exception 6: Common Fractions

In general, common fractions should be spelled out in running text.

• half of the books
• nearly three-quarters of the sample
• a two-thirds majority

When the precise value must be conveyed, the decimal or percent form is preferred.

Would you like to try out a quick quiz to test your number knowledge? Check out these easy and fun exercises from GrammarBook : Exercise 1 and Exercise 2

Comment below to let us know how you fared! All the best!

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Rules for Writing out Numbers

Reviewing the Rules

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Why do so many people find it difficult to remember the rules for using numbers in formal writing ? Probably because the rules seem a little fuzzy sometimes.

So what can you do? It's no mystery: as with anything, read and study the rules several times, and it will all seem natural, eventually.

Writing Numbers One through Ten

Spell out numbers one through ten, as in this example:

• My little brother ate four apples before dinner and became ill.
• Why do parents always check to see if babies have ten toes?

Writing Numbers Above Ten

Spell out numbers above ten, unless writing the number would involve using more than two words. For example:

• I have sixty-three dead bugs in my collection.
• My cousin has 207 bugs in his.
• This site has given me a thousand helpful hints for my homework.
• My grandmother is seventy-two today.
• My little sister had about 4,763 measles on her face.

Always Spell Out Numbers that Begin Sentences

It would look odd to begin a sentence with a numeral.

• Four hundred fifty people attended the birthday party.

However, you should try to avoid using long, clunky numbers at the beginning of a sentence. Instead of writing that four hundred and fifty people attended a party, you could re-write:

• There were 450 people at the party.

Dates, Phone Numbers, and Time

Use numbers for dates:

• My birthday is on March 16.
• He was born on Valentines Day, 1975.

And use numbers for phone numbers:

• The phone number for the school is 800-555-6262
• The international code for England is 44.

And use numbers for telling time if using a.m. or p.m.:

• The alarm will sound at 7 p.m.
• I make my bed at 7 a.m. each morning.

But spell out times when using "o'clock" or when the a.m. or p.m. are omitted:

• The alarm will sound at seven o'clock.
• I make my bed at seven each morning.
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Q. Do I spell out numbers in an APA paper?

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Was this helpful? Yes 101 No 162

Answered By: Katie Hutchison Last Updated: Apr 30, 2020     Views: 269816

Use numerals to express:

   a. numbers 10 and above       examples: 12 years old, the 57th trial, 12 cm wide

   b. numbers that precede a unit of measurement       examples: 5-mg dose, 36.3 mm

   c. numbers that represent statistical or mathematical functions, fractional or decimal quantities, percentages, and ratios       examples: multiplied by 5, .33 of the..., more than 5% of the sample..., a ratio of 15:1

   d. numbers that represent time, dates, ages, scores, points on a scale, exact sums of money and numerals       examples: 1 hr 34 min., at 3:45 am, 2-year olds, score 5 on a 12 point scale, 5th century

Use numbers expressed as words:

   a. when the number begins a sentence, title, or heading       examples: Forty-eight percent of the sample..., Twelve students improved...

   b. common fractions       examples: one fifth of the class..., two-thirds majority

   c. universally accepted language       examples: the Twelve Apostles, Five Pillars of Islam

For more information, see the Publication Manual of the American Psychological Association . You might also find help using the APA Style blog .

Links & Files

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• Purdue OWL: Wiriting Numbers

Comments (22)

• Also I believe that you write out numbers if numbers are already written in the sentence. So if you start a sentence with a number and you have another number you would write them out to keep the sentence flowing. For example: Wrong: Fourteen lucky women received 12 bracelets and 2 airline tickets when they celebrated their anniversaries today. Right: Fourteen lucky women received twelve bracelets and two airline tickets when they celebrated their anniversaries today. This is what I was taught. Am I correct? by Ronda on Oct 12, 2013
• Yes, sounds good! Thanks for the comment. by Katie Hutchison on Oct 14, 2013
• I used this sentence in a thesis paper, and my professor commented;"Use professional writing and underlined the 7,000 in the second sentence. Any idea what I did wrong? Cigarette smoke contains over 7,000 chemicals. Of those 7,000 chemicals, 69 of them are known to cause cancer. by Chris on Apr 10, 2015
• Chris, that can be frustrating because you do seem to have followed the APA guidelines. However, your instructor may be using a different style as a guide or has different preferences. When you are writing for a course and something like this comes up it's best to ask the instructor directly for clarification and guidelines. by Heidi Beke-Harrigan on Apr 11, 2015
• Yes, the professor is saying don't use the 7,000 again. It is redundant. Of the 7,000 chemical found in cigarette smoke, 69 are known to cause cancer. by Jim on Apr 21, 2015
• Question 1: If i am referring to a chapter number, how do I write it correctly in apa? i.e. Referring back to chapter 3 (three)... Question 2: If I am referring to a grade level in education, do I say Grade 2 or Grade Two? Capitalized? Thank you so much for the help by Hayley on Jun 15, 2015
• Hayley, To answer your questions... 1. For numbers less than tn you write out the number. For your example, you would write, "In chapter three, ..." 2. Same answer for question two. You will write out the number. For example, "By Grade Two, children should..." by Katie Hutchison on Jun 16, 2015
• I know this is probably too late to help the original poster, but for anyone who might be looking for help with this in the future... "Cigarette smoke contains over 7,000 chemicals; of these, 69 of them are known to cause cancer." Would be better sentence structure. Learning how to use semicolons correctly is a great thing, because VARIED sentence structure and lengths are something a proffessor looks for in a report by Jenna on Oct 03, 2015
• good articles you're so awesome by Obat Sipilis Tradisional on Oct 18, 2015
• I know that you express a percentage in words when it starts a sentence, for example: "Forty-eight percent of the workforce works is employed outside of the county." However, do you express the same percentage in words if the sentence begins with an introductory phrase? For example: "Because of the lack of industry in the county, forty-eight percent of the workforce is employed outside of the county." by JT on Oct 10, 2016
• For more information on writing numbers in a paper, see what the Purdue OWL has to say: https://owl.english.purdue.edu/owl/resource/593/01/ by Katie Hutchison on Oct 10, 2016
• Hopefully someone is still paying attention to this thread. If I am referring to questions in a study (e.g., questions of a survey), do I refer to the question written out, or numerically? Example: "Question two in the questionnaire asked participants..." or "Question 2 in the questionnaire asked participants..." Also, will this change as I start talk about questions 11-32 because these numbers are higher than 10. My thought is I would need to keep it consistent throughout the research. Thank you in advance for any input! by Rachel on Feb 20, 2018
• @Rachel - this seems to be answered in the FAQ already. It is reiterated by other sources including the Purdue OWL (https://owl.english.purdue.edu/owl/resource/593/01/) and on this academic coaching website (https://www.academiccoachingandwriting.org/academic-writing/academic-writing-blog/ii-using-apa-style-in-academic-writing-words-or-numerals) by Katie Hutchison on Feb 20, 2018
• I am starting out a paragraph using the scientific name of a chemical compound that starts with two numbers. Is this acceptable APA style or do I need to restructure my paragraph and bring the chemical name in later? Thank you! by Matt S. on Nov 04, 2018
• @Matt - so your paper will read something like, "C2H5OH can be used for....". That is not problematic to start a sentence like that. You are fine. If you have further questions, stop by the Walsh U Library. by Katie Hutchison on Nov 04, 2018
• If a number is an identifier, as in Participant 3, should it be spelled out for APA? by Pat on Dec 03, 2018
• @Pat - I would assume it should not be spelled out. "Participant 3" is more like a name in that scenario. by Katie Hutchison on Dec 04, 2018
• How do I write two numbers in sequence? For example, "there are 10 3-person crews". If I follow the write out anything below 10 rule, and I follow the use a number in a measurement rule, I would think it should be as I wrote it in the example. by Danika on Mar 10, 2020
• According to the Purdue Owl: Use a combination of figures and words for numbers when such a combination will keep your writing clear. Unclear: The club celebrated the birthdays of 6 90-year-olds who were born in the city. (may cause the reader to read '690' as one number.) Clearer: The club celebrated the birthdays of six 90-year-olds who were born in the city. by Walsh Librarian on Mar 13, 2020
• Hello there. Can I fix the language of the numbers in this paragraph any further? Phillippe Ariès (1975) identified three periods of time which views on death develop. The initial period was between the sixth and the 12th century. The following period was from the 12th to the 17th, and the last period was from the 17th up to the 20th. The last period was split further into the 17th to the 19th, and the 20th century alone. Many thanks. by Sadiq on Apr 29, 2020
• @Sadiq - Use numerals for centuries, otherwise looks good. by Katie Hutchison on Apr 30, 2020
• Much appreciated! by Sadiq on May 03, 2020

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