Please do **NOT** post your answer, but do say if you think you have solved the puzzle and how long it took. Solution on Monday.

Can you place six X’s on this noughts and crosses board without making three-in-a-row in any direction?

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# It’s the Friday Puzzle!

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Quirky mind stuff

Please do **NOT** post your answer, but do say if you think you have solved the puzzle and how long it took. Solution on Monday.

Can you place six X’s on this noughts and crosses board without making three-in-a-row in any direction?

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10 seconds. Hope I’m not doing it wrong

Easy unless I’m missing something ? 10 secs

15 secs

Solved, <5 minutes.

Slightly more interestingly, prove there are only two solutions.

A minute, because I had to open paint. I don’t think my solution is the desired one though.

If it’s right, why wouldn’t it be?

Yup, got it. Approx. 30 seconds.

15 seconds or so.

Yes. What’s the puzzle? And what’s a naught?

A “naught” is “nothing”, or the number zero: 0.

Tac-Tac-Toe for those of us on the other side of the pond.

A “naught” is the elementary particle of naughtiness. Sometimes written as “naughton”, pronounced, “Not on!”

Five minutes to clean the whiteboard, five minutes trying, 10 seconds after finding a different approach.

Nice one, I really like this puzzle!

About a minute.

yes …. sssssss

Got it on second attempt. Great puzzle.

too easy

One second

As many different solutions as you like.

Suspect my answer may not be the one Richard gives however.

30 seconds to get what I believe will be the official answer

I bet you put all siXs in the middle square, eh?

Something like that Lazy T.

I don’t want to be too specific, in case my first answer is the official one.

so, you’re playing 3D noughts and crosses – and have got a vertical column!

Maybe, but I also have a infinite number of 2D solutions.

Yes

Done

I would be interested to Chris’s proof of two solutions, because I have a proof that there is only one solution (treating rotations and reflections as equivalent).

Shift your solution 1 square in any direction and you’ll find an other one 😉

(if some of the x fall off the board, add them on the other side)

Not convinced about that shifting – I end up with a three in a row

Right, but if you DO count rotations and reflections, there are only two solutions.

sirkitkat’s idea of shifting everything one space sideways doesn’t work, because it creates a row of three where one did not exist before.

Right, overlooked something there 🙂

Got in less than 30 seconds.

First one I’ve got in a while though

Well, if you’re going to treat rotations and reflections as equivalent…

Solved less than 15min 😀

pen and paper 10 seconds

Yes, < 10 seconds

2 unique solutions, taking account of rotations etc.

Pen and paper… under 10 seconds!

Figuring it out in about ten seconds.

About half a minute or so, brainpower only (imagining the positions rather than drawing them). I wonder how solutions there’d be for twelve Xs on a 4×4 grid / twenty Xs on a 5×5 grid?

Maybe twenty seconds. It’s interesting that nobody’s chuntered about Dave’s spoiler. I guess readers have realised how easy it is to try solve the puzzle before looking at comments.

Doesn’t say anything about them having to go in the boxes…

15 seconds or so. It’s even easier if you flip it to say “Can you play three O’s in a way which stops X making a winning line? OR I’ve got it horribly wrong and embarrassed myself on the Internet. And not for the first time…

I’ve seen the photos

Brilliant, Janus. Thank you, as ever, for your laser-sharp one-liners. It would be a dark world without your wit.

re first couple of comments – – it’s a noughts and crosses board – there are certain areas which are out of bounds 🙂

and i do like the idea of the complementary problem with the 3 ‘O’s – that’s like playing the game and stopping your opponent from winning

5 seconds, else I’m wrong as rain!

By far the easiest Friday puzzle I’ve seen in a while! It took longer to find a pen and paper than to do it!

10 seconds max

10 seconds, easy one this week

solved..in 21 seconds

Yup got it in one second.

5 seconds…

what part of dont post your reply did you not get….

Keep em coming James dude

yes

It took me 3 tries and about 15 seconds. I started intuitively, and when that failed the 2nd time, I went about it algorithmically, which worked right away. It’s a nice, easy puzzle which activates our puzzler just enough to feel accomplished, which brings down our guard for upcoming, more devious games.

I love how every Friday there is a new puzzle posted and in the direction it says “Do not post the answer” but consistently, some twit within the first 0-20 comments has posted the solution. Takes all the fun out of it. Thanks Dave.

I agree Bert.

You are so right.

We could practically be related.

Do you have the same surname as me?

Now Now Children….

It’s not fair!

Bert started it!

Besides, the Self Righteous Twats have a noble lineage and are one of the oldest families in the country.

A minute

took about 15 secs

10 seconds. Then 5 more seconds with a mirror. XD

8-10 secs

Took me about 2-3 minutes.

Third attempt..

About 10 seconds

< 30 s with paper and pencil

I think there is only one solution. But if you rotate the grid through 90 degrees, you get what looks like a second solution. I count the two as just one solution. Has anyone got a solution that is not “the same” in this sense?

About 20 seconds. I found it easier to do the negative of the puzzle, i.e. placing three crosses in places where they would block all possible rows of three for the other six places.

read the question, got the answer.

Obviously it would have been more impressive if you had got the answer without reading the question.

Got it. Third attempt.

Isn’t this just completely trivial and obvious? Took about 3 seconds to draw.

Very easy one.

about 3 secs … too easy

Infinite number of solutions possible, but got one that Richard might agree with.

Took me an embarrassingly long 30 seconds to figure that out.

nice one, but easy

I also managed to put six noughts on the board at not get three in a row

1 sec

Yes. Yes I can.

Just got it in 30 seconds.

About a minute, altogether. Tried 2 different ideas, only one worked!

not too difficult. but as usual the wording allows a trivial non-solution solution. three xes slightly off center in each box makes them not align in a row. but even without such nonsense about 30 seconds

you’d be a gas playing noughts and crosses with

About 10 seconds once I finally got frustrated and picked up a pencil.

about 5 seconds

nice, if you have children, the X give 2 answer together