Composite numbers
Concept
Composite number is a whole number greater than 1 that has at least one factor other than 1 and itself.
Rules
To figure out if a number is prime or composite:
1. Find the factors of the number.
2. If the number has only two factors, 1 and itself, then it is prime.
3. If the number has more than two factors, then it is composite.
Example
Is the number 125 a prime number or a composite number?
Solution
To figure out if 125 is prime or composite find all the factors of 125.
1 x 125 = 125
5 x 25 = 125
25 x 5 = 125
125 x 1 = 125
125 has four factors: 1, 5, 25, and 125
125 is a composite number
Practice Composite Numbers
Practice Problem 1
Is this number prime or composite?
21
Practice Problem 2
Which of the following is a composite number?
Practice Problem 3
Select all composite numbers.
Prime number – A whole number greater than 1 whose only factors are 1 and itself.
Composite number – A whole number greater than 1 that has at least one factor other than 1 and itself.
Pre-requisite Skills
Identify Factors
Identify Multiples
Greatest Common Factor