Ruby hash selector pattern

fizzbuzz.rb

class Fizzbuzz
  def initialize(number)
    @number = number
  end

  def self.count(number)
    count = new(number)
    count.output_data[count.selector.to_s]
  end

  def self.count_if(number)
    count = new(number)
    count.output_if
  end

  def output_if
    result = 'Fizz' if @number % 3 == 0
    result = 'Buzz' if @number % 5 == 0         
    result = 'Fizzbuzz' if @number % 15 == 0
    result 
  end

  def output_data
    { "3" => "Fizz", 
      "5" => "Buzz",
      "15" => "Fizzbuzz" }
  end

  def selector
    output_data.keys.map { |k| k.to_i }.select do |k| 
      @number % k == 0 
    end.last
  end
end