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Sandy Wood
Brain Game: On a Count
by Sandy Wood - October 1, 2008 - 6:30 AM

bloghead_braingames.jpg

Math puzzle fans rejoice! It’s your turn.

The following series represents the numbers
1 through 8 in a specific manner.

Can you identify the 9th number in this sequence?

1, 2, 3, 2, 1, 2, 3, 4, ?

HERE is our solution.

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Comments (11)

  1. Or 3? as in:
    1,2,3,2,1,2,3,4,3,2,1,2,3,4,5,4,3,2,1,2,3,4,5,6,5,4…..
    Just another way to look at it.

    posted by SlackJack on 10-1-2008 at 6:51 am

  2. But in that case, Jack, it would have started out: 1, 2, 1, 2, 3, 2, 1…

    posted by Sandy on 10-1-2008 at 7:33 am

  3. 1+2=3, 3-2=1, 1+2=3, 3-4=-1

    i guess i was thinking too far outside of the box…

    posted by Mike S. on 10-1-2008 at 8:23 am

  4. I went with the same pattern as Mike S. And I never think outside of the box. Sometimes the simplest answer is the correct one (ie Not one involving how many letters are in the Roman numeral representation of every number!)

    posted by L.C. on 10-1-2008 at 9:41 am

  5. In Jack’s defense (and myself as I came to the same answer) who is to say that we are starting at the beginning of the sequence. I also came to the same conclusion as Jack. He identified a pattern and it works.

    posted by GBurns on 10-1-2008 at 9:56 am

  6. I’m with Jack and GBurns..I was excited to finally get a math one right. But alas, I did not

    posted by Caitlin on 10-1-2008 at 10:13 am

  7. I thought it was three. Actually, pretty sure it should be but who am I, other than a Mathe major, to say anything on the subject

    posted by DuarteIbanez on 10-1-2008 at 11:23 am

  8. I got 2 as my answer, but in a completely different manner of thinking.
    I saw this pattern unfold:

    1(23)2(123)4(2123)… 8(42123)

    posted by Lisa Marie on 10-1-2008 at 11:45 am

  9. Got the Roman numeral answer. Good one.

    In Sandy’s defense, I don’t see how the answers proposed in most of these comments represent “the numbers
    1 through 8 in a specific manner.” On the other hand, in Sandy’s (offense??), this isn’t really a puzzle to make “Math puzzle fans rejoice”!!

    posted by Betsy on 10-1-2008 at 1:19 pm

  10. i was sure i had it right when i started looking at the number of consonants in each written word. only 5 and 8 are wrong. then i realised the roman numerals thing..

    posted by johnson on 10-1-2008 at 6:04 pm

  11. I was thinking along the same lines as johnson, but i never considered to look at my wall clock (which is in roman numerals)

    posted by Josh on 11-24-2008 at 4:45 pm

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