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 Section 6.32 of the APA Publication Manual, Seventh Edition

Cases in which to always use numerals for numbers

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

Case	Example
Numbers that immediately precede a unit of measurement	5-mg dose 3 cm
Statistical or mathematical functions	multiplied by 2
Fractions or decimals (except common fractions)	1.5 2.27
Percentages	50% 75%–80%
Ratios	4:1 ratio
Percentiles and quartiles	the 5th percentile, the 95th percentile the 3rd quartile
Times and dates (including approximations of time)	30 s 10 min 3 hr 2 days approximately 4 months 2 years about 6 years ago 3 decades 12:30 a.m. 6 p.m. (or 6:00 p.m.)
Ages	5 years old, 18 years old 5-year-olds, 18-year-olds 5-year-old children, 18-year-old adults
Scores and points on a scale	scored 6 on a 7-point scale
Exact sums of money	$10 $50 in U.S. dollars
Numerals as numerals	the numeral 2 on the keyboard

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.

Number after a noun	Number before a noun
Year 5	the 5th year
Grade 5, Grade 11	the fifth grade, the 11th grade
Step 1	the first step
Level 4	the fourth level
Items 3 and 5	the third and fifth items
Question 2, Question 25	the second question, the 25th question
Table 2, Figure 5	the second table, the fifth figure
Column 8, Row 7	the eighth column, the seventh row
Chapter 6, Chapter 14	the sixth chapter, the 14th chapter

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).