.irbrc

class Integer
  def million
    self * 1_000_000
  end

  def billion
    self * 1_000_000_000
  end

  def comma
    self.to_s.reverse.gsub(/(\d{3})(?=\d)/, '\\1,').reverse
  end

  def human
    self.to_s.reverse.gsub(/(\d{3})(?=\d)/, '\\1_').reverse
  end
end