PR's 11 Pracitice PSAT

<p>On the PSAT Practice Test in PR's 11 Tests book (it's the last test) on #14 on the writing can anyone help me? Here's the problem, I put $ $ around all the parts that were underlined.</p>

<p>A number of scientists $have begun$ to speculate $whether$ life $actually began$ as crystals of clay rather $than$ as organic molecules. $No error$</p>

<p>I put $have begun$ since number is singular, isn't it? But the book says there's no error. Help, anyone?</p>

<p>No, a number of scientists is plural. I think. I believe that 'number' implies plural in and of itself. As opposed to 'group' because there can be one group, or many groups; but there can't exactly be 'many numbers' of scientists. So a number of scientists is equivalent to saying 'many scientists'; it's being used as an adjective and not as the subject...I think.</p>

<p>'A number of' is plural, but 'the number of' is singular. When they say 'a number of', the actual number isn't specified, however when they say 'the number of', there is one actual number being referred to, and so it should be singular only in that case.</p>