number_with_delimiter

# File actionpack/lib/action_view/helpers/number_helper.rb, line 200
      def number_with_delimiter(number, options = {})
        options.symbolize_keys!

        begin
          Float(number)
        rescue ArgumentError, TypeError
          if options[:raise]
            raise InvalidNumberError, number
          else
            return number
          end
        end

        defaults = I18n.translate(:'number.format', :locale => options[:locale], :default => {})
        options = options.reverse_merge(defaults)

        parts = number.to_s.to_str.split('.')
        parts[0].gsub!(/(\d)(?=(\d\d\d)+(?!\d))/, "\\1#{options[:delimiter]}")
        parts.join(options[:separator]).html_safe

      end