Q. I am editing some reports for my college. I had some good times in the ’60s, was educated in the ’70s, worked in the ’80s and ’90s, but the ’00s confuse me. What do we call them?

Q. I’m muddling through a budget document, and I cannot remember (i.e., figure out) whether dollar amounts are singular or plural. When written out at the beginning of a sentence, it seems to me that the plural works better, since the subject of the sentence seems clearly to consist of more than one item (Seven thousand dollars are needed for . . .). When presented as $7,000, though, the amount appears to be a singular subject.

Ordinarily, I would dodge the whole issue by using the active rather than the passive voice, but local custom is to place the number first in the sentence (I think that’s so our readers won’t have to waste time reading the document to see how we came up with such outrageous budget requests).

I’ve just moved, and I haven’t yet located my CMOS (I should have marked that box in neon orange); can you help?

Q. If numbers must be written out by using words, are commas added in the same places as they would be used for digits? Example: 23,504,070; twenty-three million, five hundred four thousand, seventy. Thanks!

Q. Dear style gurus, the rule is to always use the numeral with “percent,” as in “1 percent, 100 percent, etc.” Our question concerns “zero percent.” I say it should be spelled out, because your numeral rule applies to “numbers ONE through one hundred.” My co-worker says, nope, you’ve got to use 0. Who’s right? What’s the rule?

Q. In prose, when writing percentages, which is correct: 10 percent; ten percent, or 10%?

Q. In the admittedly rare circumstances when you want to write out the name of a large number, are there any agreed-upon guidelines for the usage of the word “and”? Is it “six hundred seventy-two” or “six hundred and seventy-two”? I was taught the former in grade school; a colleague was taught the latter, equally adamantly. I should note that said colleague is Canadian; is this perhaps a question of American versus British usage? All consulted manuals are, inexplicably, silent on the matter.

Q. A quandary: I’m seeing September 11th (added “th”) in the New Yorker magazine, where editing is usually superb, but somewhat antiquated. The New York Times refers to the date as Sept. 11 or 9/11. Please give me a rundown of your recommendations for this particular date, including use as an adjective (September 11 tragedy?). Or is it still too soon to have a set standard? Thanks. I’m probably the 911th person to ask you this.

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!

Q. Telephone numbers . . . what format does CMOS prefer? (800) 555-1212 or 800.555.1212 or 800/555-1212. What if the country code is required?

Q. When talking about “the turn of the century” (from 1899 to 1900), should it be “the turn of the nineteenth century” or “the turn of the twentieth century”? It seems that since the years 1800 to 1899 have been referred to as the nineteenth century, then the turn from 1899 to 1900 should be referred to as “the turn of the nineteenth century.” Please advise.