• Question: What's so weird about prime numbers?

    Asked by Jigster to Stefan, Rob, Jodi, George, Anna on 14 Nov 2014.
    • Photo: Stefan Lines

      Stefan Lines answered on 14 Nov 2014:

      I wouldn’t call prime numbers weird, but they do have an interesting property of only being divisible by themselves and one. What’s interesting is there is no known formula which allows you to find primes. There’s a group called GIMPS which uses computers to find more and more prime numbers. The largest one as of January this year is 2^57,885,161 − 1. It’s expressed in a special form, which is to do with the algorithm that GIMPS computers use to find them. It took 360,000 CPUs working at 150 trillion calculations per second 17 years to find it.

    • Photo: Jodi Schneider

      Jodi Schneider answered on 14 Nov 2014:

      One weird thing about prime numbers is that they get further apart, as the numbers get bigger. Because the bigger the number gets, the more likely it can be divided evenly by another number. The first few primes are 1,2,3,5,7,11…

    • Photo: Rob Appleyard

      Rob Appleyard answered on 14 Nov 2014:

      I think prime numbers are really weird. The definition of a prime number is really simple, but there’s no simple formula that gives you derive all the primes. Primes are also heavily tied into cryptography, so they are very useful for keeping and breaking codes.

    • Photo: Anna Scaife

      Anna Scaife answered on 15 Nov 2014:

      Weird prime number fact: if you make a doodle by writing integer numbers in a spiral then you’ll find that the prime numbers always lie on the diagonals.

      It’s called an “Ulam Spiral” after the mathematician who first noticed it (he was doodling whilst pretending to listen to a lecture).

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