It’s the Friday Puzzle!


cover 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 move just one digit and make the following equation correct:

101 – 102 = 1

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.


43 comments on “It’s the Friday Puzzle!

  1. VicinCA says:

    About 5 seconds.

  2. The Masked Twit says:

    About a minute.
    Was distracted by a weasley answer at first.

  3. Roland says:

    2 seconds for at least 1 correct answer

  4. ChrisR says:

    I’ve got a weasley answer – maybe the same as above – in about 3 minutes that would work if it was – spoiler alert –

    like the houses earlier this week. But still working on getting a more ‘proper’ one.

  5. Month Hall says:

    Is 101 – 10² = 1 permissable

  6. j1akd says:

    I have 2 answers

  7. Hugh Janus says:

    I’m certain that this is non-compliant, so I hope that you don’t mind me posting this but if you move one of the lines in the “=” sign across you get 101=102-1

  8. Barry Goddard says:

    As usual with a Richard Wiseman puzzle there are several possible answers depending on what parts of the question are irrelevant. It becomes fun to watch people argue that “their answer” is better than “your answer” because of the way they have misread the question.

    It is truely often the Blind leading the Sighted.

    In the case of today the puzzle can be solved by moving no digits at all. Just move the symbols which are not forbidden from movement by the puzzle statement. This then being an optimal solution.

    101 = 102 – 1

    • Hugh Janus says:

      As per my posting?

    • Barry Goddard says:


      We can see from the timetramps that we were both typing at the same time and we both posted the same Move No Digits solution.

      Richard would have more flexibility in his responders and allow a way to celebrate greater diversity in Thinking Styles if he asked for a range of answers. EG Move zero digits, move one digit, change one digit and so onwards.

      He is often given such a range of responses but that only sets the mona minies off grumbling that their answer was somehow purer that the better ones.

  9. I luv Spoilers says:

    Thanks guys

  10. Baker's Dozen says:

    If it’s the not equal solution then I’m outta here

  11. mgm75 says:

    I’ve got a couple but unlike the muppets above, I’m not going to post them. I’m not actually confused by the statement “don’t post your answer”

  12. mittfh says:

    It’s always worthwhile attempting to solve Richard’s puzzles before loading the comments, as there’s always some muppet with a short memory who’s forgotten the initial instruction by the time they post.

    As for my attempt, I saw a similar puzzle a few weeks ago, so worked it out very quickly. However, when I saw that earlier puzzle, I was stumped until I saw the answer.

    As Chris Tarrant used to say on WWTBAM, “It’s only easy if you know the answer!”

  13. I found myself unable to figure this out. Looking forward to solutions!

  14. I had excluded moving a line from the = to the -, because the question limited us to moving one digit. I do not define digits as the lines of operator symbols.

  15. Tibi says:

    Seriously, this “Please do NOT post your answer” direction is stupid.
    The answer is always on Google anyway.

  16. Anonymous says:


  17. fotoflex2013 says:

    Yep, saw it in under a minute

  18. Joep Bronkhorst says:

    What if I told you…

    Richard posts the answer himself in order to generate more comments?

  19. ctj says:

    10 seconds.

    wait, that was how long it took me to find the last time richard posted this puzzle:

  20. Baker's Dozen says:

    Remember it says moving a digit and nothing about making it smaller.

  21. Henry says:

    Here are a couple of puzzlers for you:

    1. Move one word to make this sentence correct: “Do post your not answers.”

    2. What curse word can you add to help the idiots above understand?

    • I Luv Spoilers says:

      1. “Do post your answers” and move the word “not” elsewhere?
      2. Genius?

    • Baker's Dozen says:

      I love unrealistic expectation.

    • Barry Goddard. says:


      Some if us have more respect for the internet than to self-censor in the face of censure.

      The internet is a place of discuss. Not a school classroom where the teachers can state “no talking while you write down the only acceptable answers”

      If Richard does not want discussion then he could post his puzzles on Google+1 where no one will see them. If he wants to micromanage the discussion he should set up a private Facebook wall.

      To post openly is to invite open replies. That is the great strength of the internet. To weaken that resolve is not a good sign. It is another step toward being ruled by Godwin;s law,

  22. French reader says:

    Lab Rat Experiment #336234 : ask them the same question than a few months ago and look how they react.

  23. Arlet says:

    HAHAHAHA I agree on the do not posts your answer reminders. Answered in a few seconds, because got confused with the word digit.

  24. Jerry says:

    As the answer has already been posted by readers who don’t respect the rules, 101 – 102 ≡ 1 without doing anything if you compute the answer in modulo 2 arithmetic. That is 101 ≡ 1 (mod 2), 102 ≡ 0 (mod2) , and 1 ≡ 1 (mod 2). Thus 101 – 102 ≡ 1 (mod 2). Math nerd? Yes, I suppose.

  25. John Cartwright says:

    About half a minute. I tried all sorts of combinations and possibilities, and I was just about to give up and read the thread to look for spoilers, when I suddenly noticed what the correct answer would be.

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