What's the etiquette of answering a 'challenge' (suggestion)

Question

When a user posts a challenge, e.g.

Given two hourglasses, one lasting 4 minutes, and one lasting 7 minutes, how do you measure 9 minutes precisely?

What's the correct form of replying to the challenge ?

Obviously, if the correct answer is there, staring you in the face then it'll be pretty tricky to not read it, thus spoiling the challenge for yourself.

Wouldn't it be best to put the answers in spoilers tags:

Like this

In that way, even if a challenge has been answered correctly, there's still some challenge left for casual readers.

Answer 1

Just to take the opposite view, I do think we should add spoilers tags, especially for questions that have very simple answers.

• Here's a question with a very simple answer, but a long and complicated solution

I don't really want the answer to be easily visible unless people are actively trying to read the spoilers. But maybe having an entire post in spoilers would look pretty terrible, and you can't see much from glancing at a full solution. So maybe only put the answer itself into a solution?

Answer 2

On the one hand, there is a clear distinction between question and answers, and (especially if there are a number of comments) the first answer may be off-screen without scrolling. On the other hand, I like how this answer gives a hint, keeping the full solution in a spoiler. On the third hand (what, you don't have one?) I don't think we really want half the answers on this site to be nothing but one big spoiler tag.

Overall, I think we should not use spoiler tags for answers. If you don't want the answer spoiled, don't go that far down the page. However, since hints would be nice for many brain-teasers here, I think we should add hints to the question, in spoiler tags. Like so

Hint 1:

To make a spoiler block, prefix it with >!.

Hint 2:

Not all markup is hidden by the spoilers. Check the preview before posting.

Answer 3

The correct form of answering a challenge is to explain the solution.

An answer that only states the solution should be considered low quality. We're discussing this in other threads: Is it on-topic to present specific logic puzzles or brainteasers as questions?, Answer-voting guidelines for challenges? (specific logic puzzles or brainteasers), Gathering chestnuts

It is nice to present the solution in two steps: some hints, and a full solution. Spoiler markup can be used to hide the full solution (the text is made visible when the reader hovers the mouse on it, or by tapping on the space in the mobile version of the site).

A ground rule of spoiler markup is that the non-hidden part must give enough information so that the reader knows what kind of content to expect in the hidden part. In the words of a Gaming SE moderator, endorsed by a Science Fiction & Fantasy moderator:

Your answer must make sense without spoiler protected paragraphs. If the spoiler is the whole point of your answer, don't spoiler protect it.

You can't have multiple consecutive paragraphs of spoiler text. This is by design: if you have so much hidden text that you run into this, you're hiding too much.