Tuesday, October 16, 2007

Prime Numbers

As most of you know, I am quick to point out prime numbers in daily life. More than anything, I like to tell people, "you're in your PRIME," when their age is a prime number.

So hat's off to my sissy la-la (AKA Amy,) for finding this excerpt for me. I can't wait to read the book.

Excerpt from The Curious Incident of the Dog in the Night-Time by Mark Haddon. Mr. Haddon used to work with autistic young people and the main character of this novel is a 15 year old boy with autism name John Francis Boone. Chapter 19 is about prime numbers.
"Chapters in books are usually given the cardinal numbers 1,2,3,4,5,6 and so on But I have decided to give my chapters prime numbers 2, 3, 5, 7, 11, 13 and so on because I like prime numbers.

This is how you work out what prime numbers are. First you write down all the positive whole number in the world. Then take away all the numbers that are multiple of 2. Then you take away all the number that are multiples of 3. Then you take away all the that are multiples of 4 and 5 and 6 and 7 and so on. The numbers that are left are the prime numbers.

The rule for working out prime numbers is really simple, but no one has ever worked out a simple formula for telling you whether a very big number is a prime number or what the next one will be. If a number is really, really big, it can take a computer years to work out whether it is a prime number.

Prime numbers are useful for writing codes and in America they are classed as Military Material and if you find one over 100 digits long you have to tell the CIA and they buy it off you for $10, 000. But it would not be a very good way of making a living.

Prime numbers are what is left when you have taken all the patterns away. I think prime numbers are like life. They are very logical but you could never work out the rules, even if you spent all your time thinking about them."

1 comment:

Anonymous said...

The algorithm described by Haddon is known as the "Sieve of Eratosthenes". There's a cool illustration of it in the Wikipedia article here:

http://en.wikipedia.org/wiki/Sieve_of_Eratosthenes

Primes (that is, extremely large primes) are used in various cryptography schemes these days to generate cryptographic keys. This works precisely because there is no known easy algorithm for determining prime factors, as Haddon more-or-less suggests.

Me, I have two years to go before I hit my next prime, haha.