On Sunday I am speaking at the Skeptics in the Tron event in Glasgow.  Hope you can make it!

So, to the puzzle.  Two word puzzles this week.

First, an easy one.  What chemical compound is represented by the following…


Second, the letters of the alphabet can be grouped into 4 distinct categories.  According to these categories, the first 13 letters of the alphabet would be classified as follows:

Category 1: AM

Category 2: BCDEK

Category 3: FGJL

Category 4: HI

Can you place the remaining letters in their correct categories?

As ever, please do NOT post your answers, but do say if you think you have solved the puzzles and how long it took.  Solutions on Monday!


  1. Apparently the real word puzzle here is “Can you work out what the words ‘please do NOT post your answers’ means?”

    Was that needlessly huffy?

    1. Absolutely agree. These selfish idiots should be banned. Ruined the Friday puzzle for everyone, whilst using bloody awful grammar.
      Richard – can you remove their comments?

  2. I’m with you Rob J, this one wasn’t so obvious to me and I would have enjoyed solving it. I wish I hadn’t scrolled down to the comments now as it has spoilt the puzzle for me.

  3. If you play the second one on the piano (one note for each category, play letters A to M in alphabetical order ), it makes a somewhat catchy tune. Use D#, F#, G#, A#.

    Any ideas for lyrics?

    (P.S. Indeed, it is disappointing when idiots post their answers. I didn’t solve it, but could have given you a modest list of things the answer isn’t.)

  4. 1st one within about 4 seconds as I’d seen it somewhere before and my memory kicked in before my logical thinking. The second one I’m struggling with so guess my brain isn’t quite awake yet 😀

    1. Think of it as a blessing. It leaves you some extra time to work on your English, and you do need to work on it quite a lot.

  5. Hah. Okay, looking at it laterally, I got the first one the second time I gave it a try. Good one.

    Stumped by the 2nd one, though. Could that have anything to do with me being a non-native speaker?

    1. It is not related to which language you speak, although in my experience you use English as well as any native. ‘Societal’ – you know what I am referring to – I know many English people who don’t know what it means, let alone how you spell it.
      Have another look… On reflection, it may become clear…

  6. Got them both! First one instantly, honest…
    Second one, almost as quick. About 30 secs in total to identify the rules, and that includes checking. I haven’t yet assigned each letter to its category, but that is immaterial.
    Quite chuffed this morning. I do look forward to your Friday Puzzles, Richard. Thank you for taking the time!

  7. Either I have the wrong solution to the second one (entirely possible) or I think you also need a rule about hierarchies for the groups – eg if a letter could fall into group A and group B you put it in group B. Perhaps we are expected to deduce that rule from the allocations given.

  8. First one very quickly, second after a minute or so.

    Rob, please don’t echo the posters who actually gave the answer away by including smug hints… 😉

    1. Sorry- I would never intentionally ruin it. I had hoped to be sufficiently cryptic.

      Seems a lot of people still haven’t got it – when they do, my hint will make sense, but hopefully not before then.

      My intention was to give a clue that would confirm an answer, not give it away.

  9. I am just so stupid! Couldn’t get either of these and had to google.

    Hint to anyone still looking? In the second one, the order is NOT important, it’s something the letters have in common.

    Hope that does not spoil it for anyone!

  10. The first one I got instantly – it’s part of an old joke:

    Teacher: What’s the chemical formula for [REDACTED]?
    Student: HIJKLMNO!
    Teacher: What?
    Student: You said yesterday that the formula for [REDACTED] was [REDACTED]…

    I might be tempted to unredact the joke on Monday for those that haven’t heard of it 🙂 It’s also a fairly popular rebus puzzle.

    As for the second, I’ve tried number of pen strokes, angles between components, number of straight / curvy lines and pronunciation but still can’t find anything linking the members of each set apart from #4.

  11. I got the second one in a few minutes, but what’s wrong with me? The first one – the easy one – I can’t figure out! HIJKL? MNO…?

  12. I think I have the second one. The first 13 letters fit perfectly with what I’m thinking, however I did end up with a couple of letters in two catergories. Not sure if that’s allowed?

    1. Oh, now I’ve got it! I was so close before, but I’ve got it now. Still can’t get my head round the ‘easy’ one.

  13. I think this may be the first time I solved a Friday puzzle before I finished reading the question. What a lovely start to the weekend. 🙂

  14. For those having trouble with the first one, take a look at a periodic table or concentrate on the ends of the string. I can’t really say much more as a hint without making the answer blindingly obvious.

  15. I still can’t wrap my head around on how people are getting the second one so quickly. It leads me to think that my solution could possibly be wrong even if it seems like a correct solution. It could be the same as the others but just really shocked that 30 seconds or so, the answer is there. Aha! Took me a minute to write all the letters down in what I think correct spot and even longer for figuring out how.

    Just shows how most of you have done lots of puzzles before. It really amazes me what experience can do!

  16. Oh, I get the 1st one now! What’s funny is that I guessed the answer at first without understanding the clue, I get it now!

  17. Unless I am wrong, in the second puzzle you COULD (but wouldn’t need to) add a fifth category. None of the letters in the first half would fall into that new category. Very few in the second half would.

    I’ve seen the first puzzle before. By the time I looked over the second I had it, but I’ve probably seen something like it before.

  18. Sorry for the hint. Unnecessary really. I think spoilers are pointless. I hoped my ‘smug hint’ was cryptic enough to pass. Hope I didn’t kill anyone’s fun.

  19. Well I didn’t get these in a couple of seconds, and after ten minutes have still not got them. Must be having blonde day- never mind will keep working on them and then when i check the answers on Monday will probably kick myself for not being able to work them out!!

  20. The last couple of weeks have been giving me trouble. This week: The first one? No idea, but I’ve never had chemistry The second one – got it in just a few seconds. I have a minor quibble with one of the letters in category # 2: One of the letters doesn’t belong (for a reason I can’t reveal w/o giving too big a hint), as I see it.

  21. The first was immediate. Too many years of solving cryptic crosswords.

    The second took half a minute; then I had to double-check I was not misreading on the basis of a particular font. I think not, but I’ll know for sure when Monday comes.

  22. The first was instant – possibly because I’m sure I’ve come across it before.

    The second took about a minute. I considered various possible schemes before I saw what it was.

    I was pleased it was such an elegant scheme.

  23. Much much easier this week – phew. 1st – a few seconds; 2nd – a few more seconds, and well under a minute for the two together. Often takes me a lot longer. Sometimes it’s luck, or practice, but these ones I think are just easier that usual… for me at least. Don’t mean to demean those not spotting these ones.

  24. first one: English is not my native language, got it by google, second one: there could be 5 categories I think, took me 10 minutes all together

  25. 1st: 30 sec.
    2nd : Thought of phonetics, vowels, cords and then one of the clues saved the day considering I couldn’t get the puzzle out of my mind as some were getting it in 30 sec. Thnx.
    Nice one Richard.

  26. sorry to all ………..it was my first time n i didnt read the last lines of the puzzle………….n i posted the answer in enthusiasm …….hope u all under stand

  27. First one I was thinking too hard but when I stepped back and took a look it was obvious.
    Second I got it reasonably quickly.

  28. A little alphabetical curiousity.

    I was brought up in both England and Scotland, and when reciting the alphabet I noticed that the Scots and the English have one funny little thing they do differently when it comes to the letter ‘J’.

    English people always rhyme ‘J’ with the letter after, ‘K’, (Jay) whereas Scots always rhyme ‘J’ with the letter before, ‘I’ (Jai).

    There you go, useless piece of information.

    Ask a Scot and an English person to recite the alphabet and you’ll see. It’s nothing to do with accents, it’s purely rhyming to either letter as how they pronounce it.

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