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Prime-Numbers.net

Where Prime Numbers mysteries are solved.

What are composite numbers?

Composite numbers are natural numbers other than 1 that aren't prime. If you take the number 1, all the prime numbers, and all the composite numbers, you'll have the entire set of natural numbers (i.e. 1, 2, 3, 4, etc.). Since prime numbers are numbers that have exactly two divisors, composite numbers are numbers that have 3 or more divisors.

Some examples

  • 4 is composite. It is divisible by itself and 1, but in addition, is also divisible by 2. Since it has a 3rd divisor, it is composite.
  • 6 is composite. It is divisible by itself and 1, but in addition, it is also divisible by 2 and 3. Since it has 4 divisors, it is composite.
  • 15 is composite. It is divisible by itself and 1, but in addition, it is also divisible by 3 and 5. Since it has 4 divisors, it is composite.