Factors, multiples and primes — a quick refresher
These three ideas are the foundation; at Stage 8 you use them to build something more powerful.
Three familiar words sit at the heart of this topic.
A factor of a number divides into it exactly, with no remainder. A multiple is what you get by multiplying a number by a whole number. A prime number has exactly two factors — 1 and itself.
At Stage 8 you put these ideas to work. The big skill is prime factorisation — breaking a number fully into primes — and then using those primes to find the HCF and LCM of larger numbers far faster than listing ever could.
The primes worth knowing by heart are . They are the building blocks for everything in this guide.
- A factor divides a number exactly, with no remainder.
- A multiple is a number multiplied by a whole number.
- A prime has exactly two factors — 1 and itself.
- Prime factorisation is the key Stage 8 skill here.