At Maths Pathway, we celebrate all things maths everyday, but especially today when we celebrate World Maths Day!
It's the perfect opportunity to come together with your students to take on an activity that will get everyone's problem solving skills working as you uncover which numbers are prime with a very useful algorithm.
We hope that your class enjoys the Prime Numbers Activity! You can check it out below and download it ready for class.
Prime numbers are numbers that only have two factors — one and themselves.
People have been interested in finding large prime numbers since ancient times. Euclid — a Greek mathematician from approximately 300 BC — proved that there are an infinite number of prime numbers. Large prime numbers have many applications, one of the big ones is their use in codes and ciphers (for more details see RSA code).
The first recorded largest prime number was 8191 found in the year 1456. More recently, using high powered computers, people have found much larger prime numbers. As of March 2022, the largest known prime has 24 862 048 digits!
There are still things that haven’t been proven about prime numbers. For example:
It can be slow to check if a number is prime, because we need to try dividing it by many numbers. The Sieve of Eratosthenes is an algorithm that was used to find prime numbers. It is a systematic approach that involves shading multiples, which can’t be prime numbers. It is called a sieve because we are sorting through all of the numbers, leaving behind the prime numbers.
Let’s try the Sieve of Eratosthenes for ourselves:
All of the circled numbers are primes and all of the shaded numbers are composites. 1 is crossed out because it is special — it is neither a prime number nor a composite number, because it's only factor is 1!