Question

What is a prime number?

Answer 1

Prime numbers aren't divisible by anything except 1 and itself, composite numbers are all real numbers that aren't prime.

Explanation:

Prime numbers are divisible only by 1 and itself, i.e. no whole numbers except 1 and itself can be multiplied to yield that number. Composite numbers have more than one set of whole number factors, such as 4, 6, 8, 9, etc.

Answer 2

See explanation...

Explanation:

An integer is a unit if it is `+-1`.

If a number `n` is expressible as `p*q` where neither `p` nor `q` is a unit, then it is called a composite number.

If a number `n` is neither a unit nor a composite number, then it is called a prime number.

So a positive integer (apart from `1`) is prime if it has no positive factors apart from `1` and itself. Otherwise it is composite.

Answer 3

Prime = Only two factors (`1,"itself"`)
Composite = Has more than two factors

Explanation:

See answer.