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As far as I understand it, it is encrypted unless the first symbol is not #. Seems to me way more likely that someone answers in a reply. Especially since a PM costs Steem Dollar. Up to @ksolymosi if this method is accepted. One upside is that the Steemit name cannot be mistaken.

Yes you cannot send a memo without sending anything (sbd or steem). We can create a simple bot, what send the money back with a memo: "you are right / wrong".

Also they can encrypt the solution and just post here. But it is a way easier to just login to steem.chat or discord and send the solution.

Btw talking about mistakes, I'm sure a bunch of people won't read the rules and just simply post the solution here.

Yes, that is my concern that people don't read the rules, but let's test it... :-) This is part of the evolution of the game...
I am thinking about the encrypted messages. Now it seems easier to send it via Discord or in e-mail but let's see how it will work out... :-)

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