Calculate the prime summands of each even number greater than 4. (https://en.wikipedia.org/wiki/Goldbach%27s_conjecture)

primes.rb

require "prime"

def prime_summands(n)
  Prime.each do |x|
    Prime.each do |y|
      return x, y if x + y == n
      break if y > n - 4
    end
    break if x > n - 4
  end
  nil
end

(4..1.0/0.0).step(2) do |n|
  n = n.to_i
  x, y = prime_summands(n)
  if x
    puts "#{n} = #{x} + #{y}"
  else
    puts "#{n} is not the sum of two primes"
    exit
  end
end