On the very last day of 2014 I was struck by a thought: Which years - in all of history - are represented by Prime numbers? I intend to expand this with other analyses.

prime_year.rb

require 'date'
require 'prime'

0.upto(Date.today.year) do | y |
  str = y.to_s
  upper = str.to_i
  prime_year, prime_parts = ''
  lower = 2 #non prime in order to fail final 'if'
  begin
    upper = (str[0..str.size-3]).to_i
    lower = (str[-2..-1]).to_i
  end if str.size > 2
  puts "#{y} is a prime" + ((Prime.prime?(upper) && Prime.prime?(lower)) ? ((str.size > 2) ? " and both #{upper} and #{lower} are prime!" : "" ): "!") if Prime.prime?(y)
end
puts "This year (#{Date.today.year}) is NOT a prime."  unless Prime.prime?(Date.today.year)