sum_of_mulitples.rb

class SumOfMultiples
  attr_reader :multiples_of
  
  def self.to(max)
    SumOfMultiples.new(3, 5).to(max)
  end
  
  def initialize(*multiples_of)
    @multiples_of = multiples_of
  end
  
  def to(max)
    multiples_sum = 0
    (1...max).each { |num| multiples_sum += num if multiple?(num, multiples_of) }
    multiples_sum
  end
  
  private
  
  def multiple?(num, multiples_of)
    multiples_of.any? { |multiple| num % multiple == 0 } 
  end
end