It has been quite a week.  For anyone that missed the fuss, we announced the launch of Dream:ON, our new iphone experiment into dream manipulation.  It was been covered by media across the world and we hope that you can take part.

So, to the puzzle….

Yesterday I bought a strip of multi-coloured cloth.  One third and one quarter of it is black, and the other 8 metres are red.  How long is the strip?

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

I have produced an ebook containing 101 of the previous Friday Puzzles! It is called PUZZLED and is available for theKindle (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.


    1. I got the answer quickly, which I thought was quite an achievement through aching in my head but I didn’t pick up on two-coloured becoming multi-coloured

    2. I’ve often said that some contributors to this page would argue that black is white. Now its seems that black is not a colour ?!? LOL

    3. @Calgacus

      Black is not a color. Black is the absence of color. A true black absorbs all visible light and reflects nothing back (in the visible spectrum).

      Let the pedantry commence!

    4. Regardless of whether or not you consider black a colour, “multi” implies many, a large number – not two.

    1. So one third and one quarter added is seven twelfhs. So the red material is five twelths = 8 meters. Easymaths

    2. Unfortunately you missed the “As ever, please do NOT post your answers”. What is it in you that feels the need to show off and spoil this competition?

    3. Brilliant anonymous. In trying to show how smart you are, all you have done is show that you are an idiot!

    4. Someone really needs to block Anonymous. There is only ONE RULE here, and it’s more than they can handle…

    1. I set up the calculations in my head, then used the calculator app on my computer to do the actual arithmetic.

  1. Well I got it and I’m not usually good at mathematical ones. Now the long wait to find out the “obvious” answer that I didn’t see (the one that tells me that I did in fact get it completely wrong)!

  2. Too easy, so lets pick nits….
    Is the 1/4 is within the 1/3 or are they two distinct bits?
    Are they stripes or bands?
    Is the material looped like a moebius?

  3. If that is a reasonably practicable way to describe its proportions, it is a very unusual piece of multicoloured cloth.

  4. It can be either 1/4+1/3 of the total, or 1/3 of the total, or 1/3 +1/12. All of those fits with the statement…

  5. How nice to have one that can be easily done in a couple of seconds without resorting to paper and pen. Unless you misread the question, of course!

  6. Easy, as always a mathematical one that has nothing to do with maths, you have to think latterally and ignore any numbers.

  7. I have the mathematical answer, and then after reading teh comments, the lateral answer. However I do not agree that the former is misreading the questions. The lateral approach makes an assumption about the way the cloth is being bought, which we don’t know is teh case.

  8. Shows how long it’s been since I added fractions – I used Excel to add them, then perform two additional calculations to arrive at the answer.

  9. There’s missing information on the color pattern! Is it striped? If so, in which direction? If not, then how is it?

    Without this information, all we can deduce is that the strip is at least 8 metre long. Or am I missing something?

  10. I guess there is something in the wording, because I don’t think this is just a simple math question.

  11. I think that I solved it in under a minute. It was so easy that I am wondering if there was some trick that I missed. Converting the fractions to percentages was a help.

  12. this is a puzzle to me. if there are two stripes running the length of it, both black, and one is 1/3 and one is 1/4 of the width. i understand that. but how can the rest be 8 meters long? unless it is all 8 meters long.

  13. “So one third and one quarter added is seven twelfhs. So the red material is five twelths = 8 meters. Easymaths”

    So says Anonymous, and is accused of spoiling, But the wording of the question says “the OTHER 8 meters is red”. So reading this as the meaning is implied, ie that you have two 8 meter halves, the first half of the strip is 8 meters, and the second half is 8 meters! So Anonymous has to fit that statement too. ie There are three possible answers so far: 8 meters, as just stated; 5x/12 = 8 meters (Anonymous); and 7x/12 =8 meters.

    The Wise Man will tell us on Monday, but Anonymous hasn’t spoiled it yet…

    1. this only works if you use the word “other” as something, er, other than what the word means in english – i.e., as an adjective referencing the part that came before. here, to be grammatically correct, other can only refer to the black portion of the cloth.

      of course, pi is exactly equal to 22/7, so all bets are off.

    2. Pi is NOT exactly equal to 22/7. Pi is irrational. (It cannot be written as a fraction). Although it can be written as a series of infinite fractions: pi = 44 – 4/3 + 4/5 – 4/7 + 4/9 – 4/11 + …

  14. I’m suspicious of the wording. Why “and” and not “plus” for the fractions? Why “other” and not “remaining”? I hope this isn’t poor wording trying to be tricky.

  15. Hmm, intriguing. Thanks for another good one, Richard 🙂 Arrived at the answer in maybe thirty seconds, off the top of my head, although something in the wording’s causing me to wonder if I’ve missed something, so I’ll be pondering it some more, just in case. Thanks again and have a fascinating and relaxing weekend 🙂

  16. It took about 30 seconds to get the answer, assuming that all the assumptions which I made about the wording and meaning of the question are correct, and/or accurate, and/or what was intended to be understood by Richard.

  17. Unless I’m having a slow day (wholly possible) there are two ways to read the question. One third and an ADDITIONAL one quarter, or the quarter is a part of the third.

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