# Racket Assignment

## Due: March 19

## Overview

The Goldbach conjecture states that every even number greater than two is the sum of two prime numbers.
For example:

6 = 3 + 3
12 = 5 + 7
38 = 7 + 31
10000 = 59 + 9941

The conjecture has never been proven, but has shown been shown to hold for every even number greater than two up to at least 4 quintillion.

You will write a program that reads in a number from the user, verifies that it is even and greater than 2, and prints out two prime numbers that sum to the value the user entered.

Example run:

Enter an even value: **91**
That number is not even.
Enter an even value: **0**
That number is not greater than two.
Enter an even value: **90**
The two primes that add to 90 are 7 and 83.

Your program should continue asking for a value until it is given an even number greater than 2.

Using packages from the Racket "Planet" repository is not acceptable.

## Tips

- Start by writing a function that tests whether a number is prime.
- Then write a function that uses this (and filter) to create a list of prime numbers from 2 to the value they entered.
- Once you have a list of primes, recurse over it testing each number.
- There may be multiple pairs of primes that add to the value, any is acceptable.
- Other functions that may come in handy:
- modulo
- member
- even?
- first
- rest

## Submitting

Submit your code by emailing the Racket file to ifinlay@umw.edu.
Copyright © 2019 Ian Finlayson | Licensed under a Creative Commons Attribution 4.0 International License.