Q. You’ve stumped me. I teach a copyediting class at Emerson College, where I’ve assigned CMOS for years as a required text. This term, I gave my class a quiz on using numbers in which one of the questions was a simple True or False about spelling whole numbers one through ninety-nine. Some students got it wrong because, they insisted, their book specified numbers through one hundred. Sure enough, several students have one version of 8.3 and the rest another. Since everyone is using the fourteenth edition, we are very curious—not to say confounded. What’s up with that quirky 8.3? Are there any other differences I should know about? I’d appreciate any insights you can offer, especially since I have already ordered the book for next semester. Thanks!

A. Ah, yes, the infamous 8.3 of the fourteenth edition of CMOS. Earlier printings of the fourteenth edition applied sound logic. Look at the two-part rule: (1) the numbers one through ninety-nine are spelled out, and (2) the numbers one through ninety-nine followed by “hundred,” “thousand,” “hundred thousand,” “million,” and so on are also spelled out. It would be redundant to write in the first part that one through one hundred should be spelled out, because one hundred is covered by the second half of the rule (from which one can extrapolate that “one” followed by “hundred” should be spelled out).

Logical as this may have been, the wording confused many of us. So we changed the first part of the rule to make it clearer: spell out the numbers one through one hundred. The rule now confuses (almost) no one, even though it is a bit redundant.

In the fifteenth edition, we retained the clarity of later printings of the fourteenth. Starting with the sixteenth, we’ve clarified that zero is also spelled out (see CMOS 9.2).