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Self Improvement Wednesday: The beauty of prime numbers

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Presenter Adam Spencer stands in front of whiteboard with numbers written on it
Self Improvement Wednesday: The beauty of prime numbers

SUBJECTS:  Maths

YEARS:  5–6, 7–8


A prime number is a number that only has two factors: one and itself.

Listen to Adam Spencer and Richard Glover discussing prime numbers.

They cover how we define these numbers and how and why prime numbers are widely used in internet encryption.


Things to think about

  1. 1.A factor is a whole number that divides exactly into another whole number. So 3 is a factor of 15, as it divides exactly into 15 (for example, 3 x 5 = 15). This means that 5 is also a factor of 15. Fifteen and 1 are factors of 15 as well, because 1 x 15 = 15. All up, 15 has 4 factors: 1, 3, 5 and 15. Find all the factors for numbers up to 20. Are there any numbers that have only two factors?
  2. 2.How does Adam explain a prime number? Have mathematicians found a formula to work out all the prime numbers? How many prime numbers are there? What is the biggest prime number every found? How many digits does it have?
  3. 3.Find all the prime numbers in the first 50 numbers. What's the largest prime number under 100? Take a challenge: find a 4-digit prime number and describe in words your technique for showing that it is prime.
  4. 4.Research the Greek mathematician Eratosthenes and create a poster on how the 'Sieve of Eratosthenes' works to determine whether a number is a prime number.



Date of broadcast: 19 Aug 2009


Copyright

Metadata © Australian Broadcasting Corporation and Education Services Australia Ltd 2012 (except where otherwise indicated). Digital content © Australian Broadcasting Corporation (except where otherwise indicated). Video © Australian Broadcasting Corporation (except where otherwise indicated). All images copyright their respective owners. Text © Australian Broadcasting Corporation and Education Services Australia is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License (CC BY-SA 4.0).

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