# When and why should you write numbers less than 10 in words?

My current strategy in my thesis and in papers is to write numbers less than 10 in words. For example, if I need to write the number 6, I write ‘six’. Recently though, I’ve been thinking this strategy adds unnecessary complications. Is there any particular reason why numbers less than 10 should be written in words?

It depends. I'd for example say "the two above equations show that the value is 5". If it is a number (result, a quantity like "5 [km]", ...) I use numerals; for "narrative" numbers up to ten or so, like "two equations" or "nine people", even up to twenty, I'd write them out. If the number comes from an equation or will be used in one, or be somehow be combined with others, I'd prefer numerals. But also consider that text is to be read as text, not as a mixture of text, symbols, and numbers. In case of doubt, write it out. Even "a thousand repetitions of the experiment...".

In absence of some style guide (or red pencil by your advisor), don't worry too much.

Answered by vonbrand on January 13, 2021

Follow the style guide and the authors' guide for your publication. Almost all such guides for academic publications include guidelines for spelling, presenting numbers, and referencing.

If in doubt, quickly scan through recent documents from the same series (so, if it's a thesis, flick through some recent theses; if it's a paper in a particular journal, have a quick read of that journal), and reproduce their formatting.

Answered by 410 gone on January 13, 2021

Many style manuals will have specific requirements regarding when to express a number as numerals or in words.

### APA Style

The APA version 6 style manual has an entire section starting from 4.31 on how to present numbers in text.

The manual does include a general rule that numbers 10 and above should be expressed as numerals, but there are a wide range of exceptions.

Should be expressed as numerals

• Any number in an abstract
• Any number immediately preceding a unit of measurement (e.g. 3 kg)
• Any number representing a statistical operation (e.g., 4 times as many people)
• times, dates, ages, scores, and points, exact quantities of money, numerals as numerals
• numbers that indicate a place in a series (e.g., page numbers, Table 1, Table 2, etc.)

There are also further exceptions for when numbers should be expressed in words

• Numbers at the start of a sentence or heading
• Common fractions
• Where the usage is common

### Why have the general rule to express numbers below 10 in words?

Compare the following:

and

• I had one-hundred and thirty-two choices.

A few possible principles:

• Numbers less than 10 are easy to read as words; Large numbers are difficult to read as words and easy to read as numerals.
• In general, conventions make life easier for writer and reader.
• There may be a slight disruption to the look of and reading of prose when interspersing numbers with words.
• A few numbers, particularly "1" (which looks a bit like "I") might introduce slight ambiguities.

Answered by Jeromy Anglim on January 13, 2021

I don't think it is an unnecessary complication, as long as you remember to be consistent. But it may not necessarily be appropriate for the document you're writing.

In English non-technical contexts, the style is often to write out numbers from one to nine as words, and then from 10 onwards as numbers (this is style used by the Associated Press and in some cases the Chicago Manual of Style). The Chicago Manual of Style also alternatively prescribes writing out numbers from one to one hundred as words. In both style guides, numbers that begin a sentence should be written out as words and Chicago specifies that, if this is an unwieldy solution, then the sentence can be rephrased. The webpage Numbers: Spell Out or Use Numerals? (Number Style 101) provides a useful guide, which goes into greater detail on good style for numbers in general documents.

However, you're likely writing a technical document, and as such, the guidelines are different, suggesting that numbers should be written with digits much more, with David A. McMurrey, author of Processes in Technical Writing, stating: 'You should use numerals, not words, when the number is a key value, an exact measurement value, or both. For example, in the sentence “Our computer backup system uses 4 mm tape” the numeral is in order.' The webpage which was the source of this quote provides helpful guidelines.

Answered by L Platts on January 13, 2021

I write numbers as words when they are used descriptively as part of the narrative, and with digits when they related to technical constants.

For example: I have two conclusions to make. First, the coefficient of 1 for reward is the best one to use. Second, the algorithm takes 34 iterations to converge.

But that's just my personal rule.

Answered by afaust on January 13, 2021

I have been taught, without justification, to write integer positive numbers from 1 up to and including 10 in words, and all the rest using numerical symbols.

But this was a general rule, when I was learning my (native) language as a youngster. Nowadays, a sub-rule also appears somehow fitting to my eyes: the distinction between whether the number is used to count the cardinality of a collection, or to inform about the magnitude of an entity.

I would write "Let two firms engaged in oligopolistic competition" rather than "let 2 firms..." (this is "counting the cardinality of a collection"). I would also write "Let fifty firms..." rather then "Let 50 firms"

But, I would write "the value of this parameter is set to 6", rather than "... is set to six".

## Related Questions

### How can I determine whether a conference is reputable?

6  Asked on January 6, 2022 by userjt

### Politicians and other students caught in plagiarism?

4  Asked on January 6, 2022 by carlos-varas-tello

### Are accepted papers going to be plagiarism checked?

3  Asked on January 6, 2022 by idriss

### Should I report two minor mistakes found in an academic paper to the journal editor or authors of the paper?

0  Asked on January 6, 2022 by atena

### Master’s and Bachelor’s theses on the same topic?

4  Asked on January 2, 2022 by baiyuxuan

### Does a 3-year PhD experience in a non-German EU university count in determining the salary for a TVL-13 (100%) position?

3  Asked on January 2, 2022 by user126706

### I’m very concerned about the mental health of my co-worker: how can I help them?

2  Asked on January 2, 2022

### How should I deal with becoming discouraged as a graduate student?

12  Asked on December 31, 2021 by aru-ray

### Is there a way to find review articles by the keyword?

4  Asked on December 31, 2021 by huammmm1

### How do I reply to a professor whether I accept his postdoc. offer?

3  Asked on December 28, 2021

### How can I export my Google Scholar Library as a BibTeX format?

7  Asked on December 26, 2021

### Would a Russian specialist degree (diploma in dentistry) qualify me a for a master’s program in Europe?

1  Asked on December 26, 2021

### What is the point of a thesis defense presentation?

3  Asked on December 21, 2021 by fwefw

### How to handle students’ disrespectfulness?

1  Asked on December 21, 2021

### Advice for struggling PhD student

5  Asked on December 21, 2021 by acmwx3

### multiple authors format for saving space

2  Asked on December 14, 2021

### How do I deal with a candidate mentioning God twelve times in their application?

16  Asked on December 12, 2021

### Is there any efficient non-linear note-taking software?

14  Asked on December 7, 2021 by user102