Composite number

Definition

A composite number is a natural number $n$ such that $n > 1$ and $n$ is not a prime number.

Remarks

Equivalently, $n$ is composite when $n = a b$ for some natural numbers $a$ and $b$ with $1 < a < n$ and $1 < b < n$. The first composite numbers are $4, 6, 8, 9, 10, 12$. The number $1$ is neither prime nor composite.

Explanations

L1 human

A composite number is a number that you can write as a product of two smaller numbers, each greater than $1$. For example, $15 = 3 \cdot 5$ is composite. You can arrange a composite number of dots as a rectangle with at least two rows and at least two columns.