This past summer, a client reached out to have me edit a document for them. One area I needed to fix was number ranges.
Here’s a snippet from the document:
Total costs of the program range from $2,505,000-3,372,000 and an average of $2,992,000, with a trend of costing less by 1-300,000 per year since 2014-15. Direct costs are higher in the first two years ($1,7-1,800,000) but then average about $1,0-1,200,00 in following 3 years. Indirect costs are higher in the first two years ($1,4-1,600,000) but then average about $1,4-1,700,00 in following 3 years.
Notice the variance to how the writer indicated number ranges?
Here is how the major style guides recommend writing number styles.
Chicago
In Chicago, the numbers changed are the second part of the range, not the first part, as was done in the above snippet.
According to 9.61 of the CMOS, numbers up to 100 (as well as multiples of 100) use all digits; numbers 101–109, 201–209, 301–309, etc, include only the changed part; and numbers 110–199, 210–299, 310–399, etc, use two digits, unless you need more to include the changed parts.
For example:
| 3–10 71–72 96–117 100–104 1100–1113 | 101–8 808–33 1103–4 | 321–28 498–532 1087–89 1796–500 11564–615 12991–3001 |
Check out this blog post on the CMOS website.
APA
APA doesn’t have explicit rules regarding number ranges, but APA does emphasize the importance of specificity and clarity in scientific writing. Thus, it’s best to not abbreviate number ranges when writing in APA style.
MLA
For numbers up to 99, MLA recommends the entire second set of numbers. For numbers above 99, use only the last two digits, unless more are needed to indicate the changed digits.
Check out this APA blog post comparing the APA and MLA methods.
Canadian Style
The Canadian Style is similar to Chicago:
| Numbers below 100 | Repeat all digits |
| First number is multiple of 100 | Repeat all digits |
| First number is 101–109, 201–209, etc | Use changed part, omit unneeded zeros |
| First number is 110–199, 210–299, etc | Use two or more digits as needed |
| Numbers of 4 digits | Use all digits if three change |
Read more here.
Also, remember to use en dashes instead of hyphens to indicate ranges, regardless of which stye guide you use. And if you use commas for large numbers, be careful about abbreviating; those commas can be misinterpreted for decimals.
So, there you have it: how to properly write number ranges. Whichever you choose, remember to not abbreviate the first number.
Did I miss a style guide? Let me know in the comments.