By David Becker
So far we have covered the general differences between MLA and APA styles and reviewed how their rules differ when creating in-text citations and reference list entries. However, a reader asked that we cover another difference between the two styles: how they present numbers, particularly ranges of numbers. I’m happy to oblige!
The two styles have very different rules for when to write numbers as words or numerals. MLA Style spells out numbers that can be written in one or two words (three, fifteen, seventy-six, one thousand, twelve billion) and to use numerals for other numbers (2¾; 584; 1,001; 25,000,000). APA Style, on the other hand, generally uses words for numbers below 10 and numerals for numbers 10 and above.
However, the MLA Handbook further notes that science writers frequently use numerals for various kinds of data, such as units of measurement and statistical expressions, regardless of size. This is similar to APA Style’s rules for presenting numerical data (see pages 111–114 in the Publication Manual for more detail).
In ranges of numbers, MLA Style includes the entire second number for numbers up to 99 (1-12; 25-29; 75-99) but uses only the last two digits of the second number for larger numbers, unless more are needed (95-105; 105-19; 2,104-08; 5,362-451). Ranges of years beginning in 1000 AD have their own rules: If the first two digits of both years are the same, include only the last two digits of the second year (1955-85; 2004-09). Otherwise, both numbers should be fully written out (1887-1913; 1998-2008).
APA Style does not have explicit rules for ranges of numbers, except for when referring to a page range or a range of dates in a reference list entry. Numerous examples in Chapter 7 of the Publication Manual show both numbers in a page range being written out in full, regardless of size, and example 23 on page 204 demonstrates the same concept applied to a range of years. These rules relate to APA Style’s emphasis on the importance of specificity and clarity in scientific writing. Thus, a range of numbers (10–40; 101–109; 5,000–5,025; 90,013–90,157) or dates (1999–2003; 2009–2012) should never be abbreviated.
I hope that this post will help those of you transitioning from MLA Style to APA Style the next time you need to include numbers in your research papers. Be sure to also check out our series of posts on numbers and metrication and our FAQ page on when to express numbers as words. If there’s still some residual confusion about numbers or any other difference between the two styles, please comment on this post, drop us a note on Twitter or Facebook, or contact us directly. Your question may be the subject of a future post!
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: multipled 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
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.