Answer to the Friday Puzzle….


coverOn Friday I set this puzzle….

Create one side of an equation that uses the digit ‘3’ five times to create the number 31.

If you have not tried to solve it, have a go now.  For everyone else the answer is after the break.

31 = 33 + 3 + 3/3

Did you solve it?

I have produced an ebook containing 101 of the previous Friday Puzzles! It is called PUZZLED and is available for the Kindle (UK here and USA here) and on the iBookstore (UK here in the USA here). You can try 101 of the puzzles for free here.


34 comments on “Answer to the Friday Puzzle….

  1. Veli Gebrev says:

    33-3+3/3 works too

    • mgm75 says:

      That’s what I got too

    • I came up with the same, first. Then the answer that was revealed above, second. I decided that the second answer was more in line with the question since “33” is a different number than “3”… yea I know… but… 3^3 just felt more in the spirit of the question.

    • Steve Jones says:

      The question only asked for the digit 3 to be used 5 times, and a digit isn’t a number (a digit is actually a symbol – hence “single digit number). That makes the use of the number 33 just as much in the spirit of the question as using two number 3s.

      Of course, if Richard worded his questions rather more tightly, then this sort of ambiguity wouldn’t arise. But, maybe, that’s the point in the first place.

    • @ScepticTank says:

      That was my solution as well

  2. Jeroen says:


  3. Steve Jones says:

    Not “the answer” as Richard claims. Just one of several possible answer possible (some of which are quite ingenious).

    Oddly Richard normally asks if there are any other answers. Not this time.

  4. Roland says:


  5. Slange Navarr says:

    Also 31=33+((3-3)/3)

    • Slange Navarr says:

      Tiresome, I must say. Someone’s borrowed my anagrammed name and wants to post incorrect answers. I can guess who it is because he’s done it before. Pathetic, Janus. Move on.

    • Hugh Janus says:

      As tempting as it may be, in this instance I can state that it is not me

    • Paul de Boer says:

      You must have a typo, because (3-3) is 0. You must mean (-3-3) which is Jeroen’s answer 31=33-((3+3)/3) but with the minus sign distributed.

  6. Barry Goddard says:

    Am I the only one around here who thinks it curious that Richard never states how long it took him to solve the puzzle?

    It seems odd that he is collecting times from the Internet (and carefully managing interactions to prevent spoilers) yet he never gives his own answer to the question he poses each week.

    And yet we never learn what he is doing with the times he has collected. If this was google we know they can put a monetary value on knowing the spread of solving times for a set of puzzles. That is more or less what google does for a living.

    But what value is Richard getting from collecting this data? Clearly it is more valuable than the costs of running the blog and licensing the puzzles. So we know how he makes money from this/ But not yet why.

    • Calgacus says:

      Barry. If there is any monetary reward for Richard through this blog, it is in the form of publicity for his books. I’m sure he is also interested in some of the curious behaviour that goes on here. He is a psychologist after all.

    • Steve Jones says:

      I think some of the replies to questions are more the domain of a psychiatrist than a psychologist…

    • Anonymous says:

      Just because you are paranoid, it doesn’t mean Richard’s not out to get you – or at least your money

    • Rod Kimball says:

      I think it’s nothing more than an easy and effective way to create traffic on his blog.

    • Barry Goddard says:

      Actually, I completely understand why Richard never says how long it took him, now I think about it.

      And obviously not everything is about making money.

      Anyway, the psychiatrist comment has hit home and I think I’ll seek help for my constant desire to troll on this website.

    • Barry Goddard says:

      @”Barry Goddard”

      A strength and a weakness of the permissive posting system allowed by Richard’s blog is that anyone can use any name. We cannot be sure that any post by “Stephen Jones” or “Huge Anus” is truely by the original person to post with that name.

      I can say that all my posts are genuine and all of them have been on topic.My posts reveal issues in the answers or the way the puzzles have been posed. They do not seek to make medical diagnoses of other posters,

      It is attractive to know that my identity is now valuable enough to be stolen. Yet my real posts can be easily verified as they will be under my email address (known to Richard) and always on topic for the original post. And always I hope relevant and informative to the discussion at hand.

      Other people who wish to be me can do so best by emulating those same strengths.

    • Steve Jones says:

      @Barry Goddard

      Fear not Barry, for they might steal your clothes, but will never be able to echo your style whilst wearing them.

  7. Eddie says:

    Where’s Halley’s Comment today or do we have to wait another 76 years for the next one?

    • MathMiles says:

      Halley’s Comment was actually me – as I was responding to someone called Halley, I couldn’t resist the name-change. But your 76 year comment is wittier!

  8. Sanjay says:

    Yeah that is really really good. REALLY good. Took me 4 days to get it.

  9. Anonymous says:

    My solution was (3x3x3)+3+3^0=31.

  10. Eddie says:

    Go raibh mile maith agaibh, Richard.

  11. lynx says:

    My first idea was this:
    The two 8s consist of a normal and a mirrored 3 put together.
    Don’t ask me why I came up with this solution…

  12. Phil H says:

    33 – 3 + 3/3

  13. Leonora says:

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