prime_value.rb

# Problem #7 from http://projecteuler.net/problem=7

def prime? x
  a = Math.sqrt(x)
  (2..a).each {|y| return false if x % y == 0}
  true
end

def prime_value(index)
  val = 3
  counter = 1
  while true
    counter +=1 if prime?(val)
    break if counter == index
    val += 2
  end
  puts "The answer is #{val}"
end

prime_value(10001)