A PRIME number is one that only has two factors, itself and 1.
A COMPOSITE number is one that has more than two factors.
PRIME numbers include 2, 3, 5, 7, 11, 13, 17 etc....
COMPOSITE numbers include 4, 6, 8, 9, 10, 12, 14, 15 etc....
Example 1
Is the following number prime or composite?
13
Answer
13 = 13 × 1
No other whole numbers multiply together to make 13.
The numbers that go into 13 exactly are called its factors.
13 only has the two factors of 13 and 1 and so it is prime.
Example 2
Is the following number prime or composite?
12
Answer
12 = 12 × 1
12 = 6 × 2
12 = 4 × 3
The numbers that go into 12 exactly are called its factors.
12 has factors of 12, 6, 4, 3, 2 and 1 and so it is composite.