class ActiveSupport::NumberHelper::NumberToRoundedConverter

def convert
  precision = options.delete :precision
  significant = options.delete :significant
  case number
  when Float, String
    @number = BigDecimal(number.to_s)
  when Rational
    @number = BigDecimal(number, digit_count(number.to_i) + precision)
  else
    @number = number.to_d
  end
  if significant && precision > 0
    digits, rounded_number = digits_and_rounded_number(precision)
    precision -= digits
    precision = 0 if precision < 0 # don't let it be negative
  else
    rounded_number = number.round(precision)
    rounded_number = rounded_number.to_i if precision == 0 && rounded_number.finite?
    rounded_number = rounded_number.abs if rounded_number.zero? # prevent showing negative zeros
  end
  formatted_string =
    if BigDecimal === rounded_number && rounded_number.finite?
      s = rounded_number.to_s('F') + '0'*precision
      a, b = s.split('.', 2)
      a + '.' + b[0, precision]
    else
      "%00.#{precision}f" % rounded_number
    end
  delimited_number = NumberToDelimitedConverter.convert(formatted_string, options)
  format_number(delimited_number)
end