<p>Why is the former wrong and the latter correct?
The number of people is amazing.
or
A number of people are amazing.</p>
<p>Also, is it correct to say numbers as a plural form of number?</p>
<p>Both are correct, but mean different things.</p>
<p>The first says that the number is amazing</p>
<p>The second says that the people themselves are amazing</p>
<p>When “the number” is used, it is singular. When “a” is used before “number” then number is plural.</p>
<p>Number in the first sentence means amount. In the second it means something like great many as in “A great many people are amazing.”</p>