code: private void evalNumber(MessageArg arg) {
      initDecimalArgsParser();
      parseArgs(decimalArgsParser);
      
      BigDecimal number = arg.asBigDecimal();
      NumberFormatter formatter = CLDR_INSTANCE.getNumberFormatter(locale);
      formatter.formatDecimal(number, buf, decimalArgsParser.options());
    }
docs: NUMBER - Evaluate the argument as a number, with options specified as key=value.