Question

What is prime factorisation and what are the steps to do it?

Answer 1

The prime factorisation of a positive integer is a list of the prime factors together with their multiplicities.
For example:
The prime factors of 12:
It is best to start working with the smallest prime number, which is 2, so let's check:
$12÷2=6$
Yes, it divided evenly by 2. We have taken the first step!
But 6 is not a prime number, so we need to go further. Let's try 2 again:
$6÷2=3$
Yes, that worked also. And 3 is a prime number, so we have the answer:
$12=2\times 2\times 3$