On Friday I posted this puzzle…..

What value should ‘x’ be in the following sequence?

16    06    68    88    x     98

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

If you turn the sequence upside down you get….

86   x  88   89   90   91

so the missing value is 87!

Did you solve it?  Any other solutions?

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.


  1. Seeing as your answer is upside down, you haven’t quite answered the question correctly. The real answer should be L8.

    1. No, the answer is 87, which is the only number in the group that, when read upside down, appears to be an upside down number. All other numbers 86, 88, 89, 90, 91, when read upside down, also appear as properly written number symbols (with the caveat that any serif on the “1” in “91” would appear odd (or even give the problem away quickly)

  2. Shouldn’t that be L8 (87 upside down)?

    …and since I believe in honesty I admit that no, this one I didn’t get

  3. I agree with the previous comments.
    The answer should be 87 upside down which doesn’t have a real value therefore it is not the proper answer.

    1. That’s why I didn’t think the answer was satisfying. Ah well, sometimes it’s not only out of the box thinking but also out of the box looking.

  4. I am beside myself now .
    How obvious does the answer and all the clues need to be.
    This was at me all week end.

    Well played Mr Wiseman.

    1. Freeze your Iphone first. Double click and slide the bottom menu to the right. Then Lock the button on the lift and the screen will not flip

    2. There is a rotational lock on iphone4 to 6. Drag the tab upward from the bottom and it is the rotation icon with a lock in the center of it. You really should read your manual or explore your phone a little.

  5. I got 87 as well, but only after reading some of the clues about “point of view” etc. That were posted on Friday. I also agree that a better answer would have been “87 written upside down.”

  6. I am proud to say I got this one but only because I’m lazy and on Friday was reading it in bed so was already reading it sideways. 🙂

  7. I agree that this puzzle doesn’t work because 7 doesn’t have an upside down variant.

    As 2 works upside down (more so in some fonts than others), I think a working sequence could be: 26 16 06 68 88

  8. Richard should have written l6 in the question instead of 16, otherwise it is a good one. I didn’t get it.

    1. The answer is 87.
      It is a simple sequence. 86, 87, 88, 89, 90, 91.
      The answer is not L8. It is not even “87 written upside down”. The orientation of the paper doesn not effect the sequence of numbers written on it.

  9. You asked for the missing value in this sequence: 16 06 68 88 x 98

    Not this one: 86 x 88 89 90 91

    Answer should be L8!! 87 is simply wrong!

  10. I got 88.
    If you swivel each digit of 68 you get 98, which is on the other side of x
    So I swivelled 88 to get 88.

    1. I agree with you that that would work, but only if there were four digits to the riddle: 68 88 x 98. The 16 and 06 would basically serve no purpose, otherwise. Nice thinking though! 🙂

  11. I thought the best answer was ’48’, but this depends on how you write your 4. Mine is basically identical to an upside-down 7, with a short line through the top of the 7.

  12. I’d say it’s 10, 20 and 30. You have to extract them from the next number. 🙂 That’s what I see in it.

    1. Not really a consensus, I don’t think. Plenty of people enjoying the answer.

  13. Okay, I was wrong. But that does fit for the first two. 16-6=10, 88-68=20. 🙂 98-x=30, which makes x=68

    1. ˙ʇsıqnɔ ʇıq ɐ sʇǝƃ puɐ pɐdǝʇou oʇuı ʇxǝʇ uʍop ǝpısdn ƃuıʇsɐd ʎɹʇ ¡¿ʞɹoʍ uǝʌǝ ʇı sǝop ʍoɥ ˙looɔ ʎllɐǝɹ sı ʇxǝʇdılɟ ˙ʍoʍ

      You can copy upside down text in and it puts it right way up again. Awesome!

  14. I was sorely tempted to make a bunch of puns on Friday about lateness, the White Rabbit and so on, but that would have been pushing the limits. Anyone who used to do calculator puzzles would get this right away.

  15. I did get this on Friday after about 5 minutes of telling myself it wasn’t a simple math problem. However, as other commenters have pointed out, 87 is *not* the correct answer.

    1. Technically yes, but saying “87” is a sure indication that one took the mental leap to solve the puzzle. Enough to pass a recruitment exam, say.

  16. 87 can be the correct answer without being upside down. The puzzle is to find x; the x in the sequence could be upside down just like the numbers. If this were the case, 87 would be the correct answer.

  17. I got stuck thinking it was the number of loops used in writing each number, that sequence starts 1,2,3,4.. Never got as far as turning it upside down.

  18. I’m happy. I got this one quite quickly after reading some of the comments and having an epiphany. Confess if I hadn’t read the comments I would probably have been scratching my head.

  19. I guessed that the numbers could be turned upside down but didn’t think that through far enough to get the correct answer, never mind there’s always next week!

  20. Sorry, a bit late on this one. Another solution to this puzzle you might find amusing is the following:

    With x=24344

    the given sequence (16 06 68 88 x 98) is the same sequence of numbers in pi starting at the 48,796,848th digit (counting from the first digit after the decimal point).

    e.g. See:
    and search for 16066888 then find the next 98 by eye. The numbers between give x.

    As you might imagine, this is not a coincidence nor magic, but rather almost statistical certitude since the digits of pi are (essentially) random for all practical purposes. The sequence 16066888 occurs roughly where you expect a random 8 digit number to occur in a large sequence. However, it is actually a lucky coincidence that that 98 occurs within a few digits of the last 88 so can be seen quickly by eye.

    Although perhaps cute, this is a kind of cheater solution because any arbitrary sequence can be found in this fashion in principle (not just limited to pi, but e, sqrt(2), and other large quasi-random sequences).

    1. yes ,indeed, your reply is most learned that I have seen..

      ,reading backwards or bottom to top or side ways is simply not a puzzle but a dizziness test?

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  22. Gosh ! Why on earth people don’t get the essence of the question rather than questioning the beauty of 7 when it is written inverted ?….. To all those gus who think the answer is L8 – do you see any other number with 7’s in the lot… That is indeed the whole purpose. Test your mental ability rather than questioning the beauty of 7 when written inverted. Common sense is so uncommon now a days after the invention of iphone may be. I am really sorry to say this.

  23. I like the “87” answer as it has you thinking out of the box. I think the proper mathematical number is 58. The response though should have read:
    16, 06, 68, 88, x, 98
    16-06 = 10
    68-88 = -20
    x-98 = 40

    The problem with that answer is that the answer falls apart when you try to determine the next number or two numbers in the sequence. You only know that the 7th number minus the 8th number will equal -50.

  24. Hi Daryl
    I agree, this question could be asked in a different way to stimulate lateral thinking
    For e.g, check the image I have created for a question and uploaded in the link below

  25. step 1 (68-16=52)
    step 2 (88-6=82)
    step 3 (98-88=10)
    step 4 (82-52=30)
    step 5 (30+10=40)
    Ans is (68+40= 108)

  26. Hi all.

    The puzzle should be given in the form of an image. It shows a car parked in a space where the ‘x’ is. The numbers correspond to the other parking spaces. You’re given the view so that the back of the space (the side furthest from the road) is towards you.

    Based on this view, you can turn the numbers upside down as it were – the perspective for ‘seeing’ the number should be viewed from the perspective of the driver. So he sees 86-87-88-89-90-91.

    Why he chose 87 remains a mystery. Perhaps he likes numbers divisible by both 3 and 29? Or is now aged 27? Or 28, if you’re picky.

  27. the answer is 128 the difference between the first two number is 10 16 and 6 and starts with d larger number 16. the diff between the 2nd sets of numbers is 20 68 and 88 and it starts with the small to the bigger number and since its a sequence and follows a pattern, d last sets of numbers must be 30 diff apart which make d likely candidates 68 n 128 and since a number can not repeat in a sequence d answer is 128

  28. Hello! I found 78… because after you find 87, don’t you have to look upside down again? What do you think?

    1. I think it is 78, also. I disagree with all the 87 answers. Looking at the numbers right – side up, knowing they are relfected, u could see the answer is 78…..lol… I understand how people get 87, but don’t think it is the right choice.

  29. With this illustration we agreed with 87 is a correct answerhttp://static3.businessinsider.com/image/5391c8bf6bb3f73e4603e62c-600-422/what-parking-space-number-is-the-car-parked-in-english-translation.jpg

  30. Apologies, I meant to say you 87 is not that obvious. You take 16 and 06, which give a difference of ten in the order big, small. Then follow 68, 88 where the difference is 20, in the order small, big. So logically the next difference is 30 in the order big, small again. Add 30 to 98 to get 128. Therefore I reject your answer of 87 on the basis that you cheated! :-))

  31. 87 ANSWER IS WRONG !!!!!!

  32. I think there is another way to solve that puzzle.it is little bit a type of mathematical puzzle.
    16 06 68 88 × 98
    If we go in this manner -10 +20 -30 +40 -50 +60 ………………
    ( × – 30)=98
    So value of × would be 128

  33. You’re wrong. 87 is the correct answer. Though this view shows the other spots as numbers upside down we can all agree because of the sequence the answer is 87. It doesn’t say what would the number of this parking slot look like from this view. It says what is the number of the parking slot? Yes from this view the 87 would look like L8 in this picture. But that doesn’t change the number of the actual slot.

  34. Consider alternate sequence:
    06, 88, 98
    Here 88-06 = 82
    98-88 = 10 (= 8+2)

    On similar logic
    16,68, ?

    Here 68-16 = 52

    So next number will be (5+2) + 68 == 75

  35. I think 93 is the ans…..
    Que is 16 06 68 88 _ 98 ?
    Ans: 61 60 86 88 _ 89
    So ..61 – 60 = +1
    86 – 88= -2
    X – 98=+3

    1. It not a matter of any formula. The answer is from looking at the numbers upside-down. 87

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