Prime Numbers

A prime number is a natural number greater than 1 that cannot be formed by multiplying two smaller natural numbers.
The first few prime numbers are 2, 3, 5, 7, 11, 13, 17, 19, 23, 29 and so on.
However, remember that 1 is not considered a prime number, as it only has one factor.
A prime number is a number that has exactly two distinct positive factors: the number itself, and 1.
If a number has more than two factors, it is called a composite number.
An important method in prime numbers is factorisation, where a number is written as a product of its prime factors.
To factorise a number, start dividing by the smallest prime number, which is 2, and continue dividing by prime numbers until only prime numbers are left.
Prime numbers play a central role in a concept known as the Fundamental Theorem of Arithmetic. This theorem states that every integer greater than 1 either is a prime number itself or can be factorised as a product of prime numbers, and this product is unique apart from the order of the factors.
You can also use the Sieve of Eratosthenes to quickly find all primes less than a given number. This ancient method involves crossing out multiples in a list of numbers from 2 to the desired range.
Key skills to have when working with prime numbers include the ability to list factors, determine whether a number is prime or not, and decompose a number into its prime factors.
Practice is the key to master these skills. Choose a range of numbers and practise identifying prime numbers and carrying out prime factorisation regularly.