is 1 a composite number or a prime number?

Answer 1

prime.

Answer 2

how do u know?

Answer 3

good question. That is the way I learned it, years ago. Now that I look, I am wrong, it has been redefined. Thanks for asking.

Under current definitions, 1 is neither prime nor composite.
Read this:
http://en.wikipedia.org/wiki/Composite_number

Answer 4

and
http://en.wikipedia.org/wiki/Prime_number