A multiple of a number is found by multiplying the number by any whole number.
What are the first six multiples of 6?
To find the first six multiples of 6 multiply 6 by 1, 2, 3, 4, 5 and 6 to get:
6, 12, 18, 24, 36 and 42
Therefore, any given number can have infinitely many multiples. One way of checking if a number is a multiple of another number is by using divisibility tests.
A factor (also known as a divisor) of a number is a whole number that can divide exactly into it.
Factors come in pairs and is explained below:
What are the factors of 20?
1 and 20, 2 and 10, 4 and 5.
So, in order, the factors of 30 are:
1, 2, 4, 5, 10 and 20.
Points to note:
- A number will have an odd number of factors when a number is multiplied by itself and the factor pairs are repeated.
- If a number has an odd number of factors, it must be a square number.
Prime numbers are whole numbers with only two factors (1 and the number itself).
For example, the number 19 has only two factors, 1 and 19.
Therefore, 19 is a prime number.
The number 1 has only one factor, 1 and so is not a prime number.
Also, 2 is the only even prime number.