Binary Conversion in Elixir

binary_conversion.ex

# Binary conversion: take a number 7, output "111"
defmodule Randori do
  def helper(x, s \\ "")

  def helper(0, "") do
    "0"
  end

  def helper(0, s) do
    s
  end

  def helper(x, s) when rem(x,2) ==0 do
    helper(div(x, 2), "0" <> s)
  end

  def helper(x, s) do
    helper(div(x, 2), "1" <> s)
  end

  def conversion(x) do
      helper(x)
  end

end

IO.puts "started"
IO.puts Randori.conversion(7)
IO.puts Randori.conversion(2)
IO.puts Randori.conversion(0)
IO.gets "what is the number? "
IO.puts "ended"