A number of means several, so it takes a plural verb: “A number of guests are late.” The number of means the total, so it takes a singular verb: “The number of guests is rising.” One little article—a or the—changes what the sentence is talking about.
That sounds manageable until you’re halfway through a sentence, staring at guests, and wondering whether the verb should be is or are. The trick is not to count how many people are involved. It’s to ask what the sentence says about those people.
“A Number of” Means “Several”
Imagine a café with a line out the door:
A number of customers are waiting outside.
You could swap a number of for several without changing the basic meaning: “Several customers are waiting outside.” You’re talking about customers, not a figure on a spreadsheet. That’s why the plural verb are feels at home.
The same pattern works with other verbs:
- A number of readers have noticed the typo.
- A number of questions remain unanswered.
- A number of cupcakes were missing by noon.
The phrase doesn’t tell us an exact quantity. There might be six questions or sixty; the point is that more than one question remains. As The Chicago Manual of Style explains in its answer about “a number of” and verb agreement, the expression works much like some or several.
Here’s a useful warning: don’t let the singular-looking word number lure you into writing “A number of customers is waiting.” In this everyday meaning, the phrase points to the customers as a group of individuals. Are is the standard choice.
“The Number of” Means “The Total”
Now picture the café manager checking a tally:
The number of customers is increasing.
This time, the sentence isn’t saying that the customers themselves are increasing. It’s saying that the total is increasing. The number is the singular thing we’re discussing, even though customers is plural and sits closer to the verb.
Try replacing the number of customers with the total: “The total is increasing.” The singular verb becomes much easier to hear.
More examples:
- The number of available seats is limited.
- The number of applications has doubled.
- The number of mistakes was surprisingly small.
Even if the total turns out to be 10,000, we’re still referring to one total. Its size doesn’t turn number into a plural noun. The Chicago Manual of Style illustrates the same distinction: “the number of” takes a singular verb, while “a number of” takes a plural one.
If choosing between number and amount is another stumbling block, our guide to “amount” versus “number” tackles that separate question. First choose the right noun; then decide whether you mean several things or their total.
Same Noun, Different Spotlight
The contrast is clearest when everything except the opening phrase stays nearly the same:
A number of volunteers have signed up.
The number of volunteers has increased.
In the first sentence, volunteers did something: they signed up. In the second, a total changed: it increased. The verbs differ because the sentences point their spotlights at different things.
Here’s another pair:
A number of library books are overdue.
The number of overdue library books is growing.
No books transform into a single giant book in the second sentence. We’ve simply stopped talking about what the books are and started talking about how many there are.
This is why “make the verb agree with the nearest noun” isn’t a reliable shortcut. In “The number of books is growing,” the nearest noun is books, but the singular verb belongs with the number. For a broader look at traps like this one, see our guide to subject–verb agreement without overthinking.
The Two-Swap Test
When you’re editing, you don’t need to diagram the whole sentence. Make one quick substitution:
- Can you replace the phrase with “several”? Use a plural verb.
“A number of emails have arrived” becomes “Several emails have arrived.” - Can you replace it with “the total”? Use a singular verb.
“The number of emails has increased” becomes “The total has increased.”
Think of the test as checking the sentence’s job description. Is it describing several people or things? Or is it reporting a figure about them?
The substitution is especially handy when extra words pile up between the phrase and the verb:
The number of messages in the inbox after the long weekend is alarming.
All those messages—and the entire long weekend—can distract you. Strip the subject down to the total, and you get “The total is alarming.” Crisis averted, though perhaps not the inbox crisis.
What About “A Large Number of”?
Adding an adjective doesn’t usually change the everyday pattern:
A large number of fans are waiting.
A small number of fans are waiting.
The number of fans is unknown.
Large and small tell us something about the size of the group. They don’t turn “a number of fans” into “the number of fans.” In ordinary statements about the fans, the a number of expression still takes a plural verb. A GrammarBook discussion of these word choices gives the same practical guideline.
There is a nuance worth knowing, though: “a number” does not always mean “several.” In “An even number of chairs is required,” you’re talking about a mathematical property of the total—it must be divisible by two—not merely saying that several chairs are required. That’s a different meaning from “A number of chairs are missing.” The Chicago Manual of Style notes this distinction in its discussion of “an even number.”
For most emails, essays, and reports, the several versus the total test will get you where you need to go. If you’re discussing the number itself—whether it’s even, odd, or a particular figure—pause and check the meaning rather than applying a slogan automatically.
A Sentence Can Need Both Verbs
Some sentences contain a verb for the people or things and another verb for their total:
The number of guests who have arrived is higher than expected.
Why have and is? The guests have arrived. The number is higher than expected. Each verb has a different job.
You can untangle the sentence by splitting it in two: “Guests have arrived. Their total is higher than expected.” Nothing has broken the rule; there are simply two subjects to keep track of.
The reverse works too:
A number of guests who have arrived are waiting outside.
Here, both have and are relate to the guests. This distinction matters because changing every verb in a long sentence to singular—or every verb to plural—can create a new mistake while you’re fixing the first one.
Try It Without Peeking
Choose the verb that fits each sentence:
- A number of neighbors has / have offered to help.
- The number of neighbors at the meeting was / were higher than expected.
- A surprising number of cookies is / are gone.
- The number of cookies in the jar has / have dropped.
- The number of students who has / have registered is / are growing.
Answers: 1. have—several neighbors offered. 2. was—the total was higher. 3. are—we’re talking about missing cookies. 4. has—the total has dropped. 5. have, is—the students have registered, and their number is growing.
If the last one made you hesitate, that’s normal. English tucked two agreement decisions into one sentence and hoped you wouldn’t notice.
The Takeaway
A number of people are doing something; the number of people is a figure you can count, compare, or watch change. When in doubt, replace the first phrase with several and the second with the total.
That tiny switch from a to the doesn’t just change the verb. It changes what you’re talking about—and once you spot that, the verb usually falls into place.