Today someone has posted a [question](https://math.stackexchange.com/questions/1266217/the-ideal-p-always-factors-in-the-ring-of-integers-of-mathbb-q-sqrt2-s), and after less than 30 minutes he also posted an answer to his own question. I've flagged the mods and they declined my flag.

If I remember well, in the past, user Makoto Kato did similar things, using M.SE as its own database, and he was highly criticized (suspended?) for doing so. 

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> Is this now an accepted way to use M.SE?
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**Edit.** For those who think this happened only once to this user, let me give at least another one: [An isometry of Hilbert spaces using the Radon-Nikodym derivative](https://math.stackexchange.com/questions/459122/an-isometry-of-hilbert-spaces-using-the-radon-nikodym-derivative). (Here he posted an answer after 12 minutes!)

Let me make my point a little clearer: 

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> Is it okay to post a question you already know the answer with the only purpose to answer it by yourself?
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**Later Edit.** There is a related question [Can I post a question and an answer just because I think it helps others?](https://math.meta.stackexchange.com/questions/15017/can-i-post-a-question-and-an-answer-just-because-i-think-it-helps-others) and an interesting answer posted there by @quid.