Prime and Composite Numbers

Prime or Composite: Learn

A prime number is a whole number that only has two factors which are itself and one. A composite number has factors in addition to one and itself.

The numbers 0 and 1 are neither prime nor composite. They are too special because they represent nothingness (zero) and wholeness (one), so the idea of having factors for 0 and 1 does not make sense. Without a concept of factors, we cannot classify 0 or 1 as prime or composite. Only whole numbers larger than 1 can be classified as prime or composite.

The divisibility rules might help you identify composite numbers. For example, all even numbers are divisible by two, and so all even numbers greater than two are composite numbers.

However, there is no overall pattern for identifying primes and composites, other than checking for possible factors. When checking for factors, make a list and check for divisibility of every number starting at 2 and working your way up until the quotients of the divisions start to come out smaller than the divisors.

To get you started, all of the prime numbers between two and one hundred are 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89 and 97.

Prime or Composite: Practice

Identify whether the number is prime or composite.


Is the number prime or composite?

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