GCSE Secondary Maths Age 13-17 - Number: Prime Numbers - Explained

The video tutorial covers identifying prime numbers between 20 and 30, explaining the concept of prime numbers as having only two factors: 1 and itself. It demonstrates the process of eliminating non-prime numbers by checking divisibility and highlights that 23 and 29 are the only primes in the given range. The tutorial also addresses the uniqueness of 2 as the only even prime number, explaining that all other even numbers have additional factors, making them non-prime.

Which of the following numbers is a prime number between 20 and 30?

• 22

• 23

• 21

• 24

Why is 25 not considered a prime number?

• It is less than 30.

• It has more than two factors.

• It is an even number.

• It is a multiple of 3.

Which of these numbers is a prime number?

• 28

• 27

• 30

• 29

What makes 2 unique among even numbers?

• It is the only even prime number.

• It is a multiple of 4.

• It is greater than 10.

• It is the smallest even number.

Why can't even numbers other than 2 be prime?

• They are divisible by 2.

• They are all greater than 10.

• They have more than two digits.

• They are all odd numbers.