Q. In the sentence “It happened on the twenty-fourth of July,” should the date be spelled out or a numeral? CMOS 9.31 only addresses the treatment of ordinals when the month is not mentioned.

Q. When referring to decimals from zero to one, are they singular or plural? For example, “The road extends for 0.8 mile(s).” A coworker is arguing it is singular since it is not more than one, while I believe it to be plural since we are now talking about multiple pieces of one (eight tenths). If it is singular does the same hold true for similar numbers written as fractions?

Q. Regarding spelling out round numbers over one hundred—how should we handle numbers like 1,500? It’s more round than a number like 1,543, but it’s also less round than a number like one thousand. And if it should be spelled out, which is preferred, “one thousand five hundred” or “fifteen hundred”? Thanks!

Q. In the context of computer bits, would you make an exception to the rule about spelling out numbers under 10 (Chicago’s alternative rule), or would you still spell out “zero” and “one”? For example, “Information is represented in bits as 0s and 1s.” Is that correct?

Q. What is the CMOS stance regarding the use of numerals for a year at the beginning of the sentence? For example, “1980 was indeed a good year.” I see that AP allows it, but I don’t know if you do.

Q. I am preparing an online archive. Many of the items are audio or video recordings. I’ve fruitlessly searched CMOS for the proper way to indicate the total time of a recording—for example, thirty-five minutes and thirty-three seconds. 35 min. 33 sec.? 35m:33s?

Q. Which of the following is correct or preferred? I’m guessing it’s the first option. I’m working on a very important, time-sensitive document, and everything has to be correct according to CMOS.

She’s number one in my book.
She’s number 1 in my book.
She’s No. 1 in my book.
She’s no. 1 in my book.

Q. Why, in many book titles that include ranges of years, is Chicago style for inclusive numbers not followed? As I understand it, Chicago style is to elide the first two digits of the four-digit second number if they are the same as the first two in the first number of the range. The publisher I work for, like many others, follows that rule in general text. But consider, for instance, the subtitle “Self-Portrait of an Actress, 1920–1956.” Do most readers prefer to see titles with ranges of years styled like this one? 

Q. Can you inform me how you would recommend writing out “10:05 a.m.” if an author is very set on using words rather than numerals?

Q. Should hundred be repeated in spelled-out number ranges such as “one to three hundred” (meaning 100 to 300)?