Every year GCHQ, the UK’s intelligence and security organisation, sets some challenges within a Christmas card. These are supposed to be for kids (for goodness sake), but they present a pleasingly solvable challenge for adults. I thought it would be nice to share.

Front of the card:

I’ve only tried the first one so far and the answer is SEAWEED

I concur with the previous posters, in addition I believe the answer to the third “Coding” puzzle is carpentry.

Minor hint for the final puzzle: I think calling it “Mathematics” is misleading, I would say it’s a word puzzle.

Thanks for posting this! I’ve got a book of their ‘adult’ puzzles and simply don’t have the time/intelligence to get some of them. These are just right for a momentary diversion.

Although I was joking about the secret message above, I’ve done the what3words bit properly and it all works, although the actual message is even less interesting than the fake one I mentioned above.

Don’t overthink it. Just count around each wheel 20 letters in the appropriate direction for the cog.

I got stuck because I didn’t initially see the “belts” between the second and third cogs, and the fourth and fifth cogs.

And I got stuck because I did see the belts, and assumed that they were equal-radius (hence, 2.5 full rotations of one gear would be 2.5 full rotations of the next).

I solved the cryptogram on 7, but I’m missing something, er, obvious. First solve the code/Identity a 4-letter word/Look everywhere/Maybe it’s obvious. The whole thing is a card, maybe that’s it?