public void add(Integer... numbers) {
        int total = Arrays.asList(numbers)
        .stream()
        .mapToInt(Integer::intValue)
        .sum();
        
        String output = Arrays.asList(numbers)
        .stream()
        .map(n -> n.toString())
        .collect(Collectors.joining("+"));

        System.out.println(output + "=" + total);
    }