grammaticality - "The number of residents has grown" vs. "the number of residents have grown"

Duplicate:
“A number of students” vs. “the number of students”
“Number of attempts per question is unlimited” or “are limited”?
“A number of questions has been asked” or “have been asked”?

1. The number of residents has grown.


2. The number of residents have grown.

Which of the above sentences is grammatical? Since has should stick with singular nouns and have with plural ones, I guess (2) should be correct, but I'm not sure.

Answer

It’s singular, has, because number is the head of the subject phrase. It would be plural if the subject phrase was a number of residents in, for example, A number of residents have complained. There, a number of is a pre-modifying element.