A *prime number* is a whole number, greater than 1, that can only be divided by itself and the number 1. It is known that all even numbers between *4* and *300,000,000,000,000,000* are equal to the sum of two primes (a fact that is believed to be true for all larger even numbers as well, and called the Goldbach Conjecture).

For example, *30 = 7 + 23*. There are two other ways of expressing *30* as the sum of two primes, which are *11 + 19* and *13 + 17*. These are the only ways of expressing *30* as the sum of two primes, since the order of the numbers in the additions does not matter.

- Write a program which inputs a single even number (between
*4*and*10,000**inclusive*) and outputs a single number which is the number of different ways the input can be expressed as the sum of two primes. - There are four ways of expressing
*46*as the sum of two primes. What are they? - There are many
*odd*numbers which cannot be expressed as the sum of two primes. How many such numbers are there between*4*and*50?*

This question was taken from the 2008 British Informatics Olympiad.

If you can't program, there is no reason you can't attempt questions 2 and 3.

Good luck and have fun.

Louis

"Computer science is no more about computers than astronomy is about telescopes."

~ Edsger W. Dijkstra

Solution:-

This is my code:

https://github.com/ldhmachin/BIO-2008-Goldbach/

This is the answer to Question 2.

This is the answer to Question 3.

"Computer science is no more about computers than astronomy is about telescopes."

~ Edsger W. Dijkstra

I wrote up some python code for this. Here it is:

https://docs.google.com/document/d/1RWe35UXM9NO-iuRX0MhgTTQ6vAQoNXQyA0MaRcKULUY/edit

my answers to the questions are also on this.

That one guy that's always on

Looks good Lucas!