multiples_up_to.rb

def multiples_up_to(multiple, limit)
  # Rather than calculate every number and evaluate whether that number is a multiple, there's a handy bit of math I found that checks how many multiples are in any number of integers.
  # We then keep adding up the "multiple", doing basic arithmetic until we reach the limit
  start = 0
  ((limit - multiple + 1)/multiple).times do
    start += multiple
    p start
  end
end

multiples_up_to(3,200)