A factor is number that can divide another number without leaving a remainder. For example, the factors of $8$ are $1$,$2$,$4$ and $8$ itself.
What do you think?
1) Which of the following is a factor of 12?
- 60
- 24
- 3
- -24
2) Which is not a factor of 24?
- -14
- 4
- 1
- 3
Highest common factor (HCF)
This is the largest number that can divide a list of numbers exactly. It is also referred to as the greatest common divisor (GCD).
Finding the HCF of two numbers
We can use a table method to find the HCF of multiple numbers:
Prime numbers
These are numbers with exactly two factors - 1 and themself. The first few prime numbers are: 2, 3, 5, 7, 11, 13, 17, 19,…
Composite numbers
These are numbers with more than two factors.
The prime factorization of a composite number
We can express a composite number as the product of only prime numbers - this is referred to as the prime factorization of that composite number.