private Double isValidAnswer(Double result) {
        result = Math.round(result * 100.0) / 100.0;
        String comparedFloatPoint = ("" + result).split("\\.")[1];
        if (comparedFloatPoint.contains("E") || comparedFloatPoint.length() > 1)
            return null;
        long point = Long.parseLong(comparedFloatPoint);
        if (point > 10) {
            return null;
        }
        return result;
    }