1. What are Prime Numbers?
A prime number is a natural number greater than 1 that can only be divided by 1 and itself, without leaving a remainder. In other words, a prime number only has 1 and itself as factors.
The smallest prime number is 2.
Some examples of prime numbers are:
2, 3, 5, 7, 11, 13, 17, 19, 23, 29, …
2. Composite Numbers
A composite number is a natural number greater than 1 that is not a prime number.
For example, 4 is a composite number, as 4 has 1, 2 and 4 as factors.
3. Prime Factorisation
Prime factorisation is the process of expressing a number as a product of prime numbers.
To write a number as a product of prime numbers:
- Continuously divide the number by prime numbers until only primes remain.
Example 1: Write 60 as a product of its prime numbers.
60 = 2 x 2 x 3 x 5 = 2² x 3 x 5
Example 2: Write 3500 as a product of its prime numbers.
700 = 2 x 2 x 5 x 5 x 5 x 7 = 2² x 5³ x 7