Prime numbers are some of the most useful numbers in maths and they can help you out a lot!
Therefore, it is a really good idea to understand how to identify them and to commit, at least the most common ones, to memory.
Definition: A prime number is a number that only has two positive factors.
What this means in reality is that you can only divide a prime number by two things: 1 and itself.
So 17 would be a prime number because you can only divide it by 1 and 17.
But 15 wouldn't be a prime number because you can divide it by 4 things: 1, 3, 5 and 15.
Numbers that aren't prime numbers are called composite numbers.
What are the most common prime numbers?
You are expected to know the prime numbers up to 30, so you need to memorise this list:
2, 3, 5, 7, 11, 13, 17, 19, 23, 29
In this activity, you will practise identifying prime and composite numbers so that you can use these facts to help you solve complex problems and mental computations quickly.