Composite numbers can be defined as numbers that have more than two factors. Numbers that are not prime are composite numbers because they are divisible by more than two numbers.
Examples:
- Factors of 4 = 1, 2, 4 i.e.
Since 4 has more than two factors. So, 4 is a composite number.
- Factors of 6 = 1, 2, 3, 6
Since 6 also has more than two factors. So, 6 is also a composite number.
Properties of Composite Numbers:
- Composite numbers have more than two factors
- Composite numbers are evenly divisible by their factors
- Each composite number is a factor of itself
- The smallest composite number is 4
- Each composite number will include at least two prime numbers as its factors (Eg. 10 = 2 x 5, where 2 and 5 are prime numbers)
- Composite numbers are divisible by other composite numbers also
Types of Composite Numbers:
There are two types of composite numbers:
(i) Odd Composite Numbers
Composite numbers with an odd digit in the unit’s place are odd composite numbers. In simple words, all the odd numbers that are not prime numbers are odd composite numbers.
For example: 9, 15, 21, etc.
(ii) Even Composite Numbers
Composite numbers with an even digit in the unit’s place are even composite numbers. In simple words, all the even numbers except 2 are even composite numbers. This is because no even number (except 2) can ever be a prime number.
For example: 8, 12, 14, etc.
