The number of errors that you’ll find in this sentence from Yahoo! Celebrity is close to one:
It’s so close to one, that it is one. And it’s a common subject-verb disagreement when the subject is number. Here’s what the American Heritage Dictionary says about number as a collective noun:
As a collective noun number may take either a singular or a plural verb. It takes a singular verb when it is preceded by the definite article the: The number of skilled workers is increasing. It takes a plural verb when preceded by the indefinite article a: A number of the workers have learned new skills.