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Pattern Recognition Brain Teaser

Here’s a puz­zle to test your abil­i­ty to find a pat­tern and test it against more data.

In this table, each row across fol­lows the same pat­tern of num­bers. See if you can dis­cern the pat­tern and fill in the miss­ing num­ber in the bot­tom row. For added chal­lenge (or com­pe­ti­tion), time how long it takes you to com­plete the puz­zle. Then, pass it along to some­one else and see if they can solve it faster. The slow­er one has to cook din­ner!

7 4 8
3 9 7
6 5 10
? 8 4

Exec­u­tive func­tions, like plan­ning, and spa­tial pro­cess­ing are han­dled by your frontal lobes.

Have you solved it yet? If not, here’s a hint:

If you read your fig­ures like words in the West,
then mul­ti­ply your efforts and sub­tract the rest.

Keep read­ing for the answer and solu­tion.

(7x4)-8 = 20

(3x9)-7 = 20

(3x8)-4 = 20

The answer is 3.


More brain teas­er games:

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38 Responses

  1. Michelle B says:

    Sigh! Could not get this teas­er either. How­ev­er, I did get the clue (some­what). But what I found inter­est­ing is when I did repeat men­tal­ly the expla­na­tion, my brain felt, how can I say, a sense of well­be­ing, like it was being nour­ished. Are all brain teasers not cre­at­ed equal in this regard? I remem­ber men­tal dis­tress after doing oth­er ‘brain teasers’ years back.

  2. Alvaro says:

    Hi Michelle, you are prob­a­bly expe­ri­enc­ing the release of dopamine and oth­er neu­ro­trans­mit­ters that cre­ate that sense of well­be­ing as you iden­ti­fied a pat­tern. Which is why learn­ing, brain teasers, trad­ing suc­cess­ful­ly, and oth­er “brain exer­cise” activ­i­ties can be quite addic­tive!

    A dif­fer­ent appli­ca­tion, but illu­mi­nat­ing

  3. Maryanne Silber says:

    Looked at the prob­lem dif­fer­ent­ly. I didn’t get your solution…but I had fun. I said 7+4+8=19

    In try­ing to make a sec­ond “pair” that were equal I put 9 in your emp­ty spot.

    Well…I’v always been bad at math and any form of log­ic. But I had fun!

  4. Maryanne Silber says:

    OOOPS…I can’t type either.
    3+9+7=19 also “I’ve”

  5. Caroline says:


    While the dopamine rush that Alvaro men­tions above hap­pens when you solve the puz­zle or under­stand the answer (the “aha!” moment), work­ing through the puz­zle is good brain exer­cise in and of itself (you’re get­ting chal­leng­ing and nov­el men­tal stim­u­la­tion). And you did your math cor­rect­ly with a log­i­cal pat­tern, so you’re not that bad at either task! The typos … well those may be more due to a lapse in atten­tion and hand-eye coor­di­na­tion. Keep work­ing and hav­ing fun with it!

  6. shreyas says:

    came up with some­thing dif­fer­ent, in terms of a rela­tion­ship. sub­tract each num­ber from 9, take the absolute val­ue of this dif­fer­ence, and sum them, the total is always 8 ie. 7–9=-2=2 (absolute), 4–9=-5=5, 8–9=-1=1 so 2+5+1=8
    sim­i­lar­ly in the sec­ond and third rows, sum is 8. there­fore the num­ber in the fourth row can be either 7 or 11.
    con­vo­lut­ed solu­tion and non-unique.
    won­der what that says abt my brain!

  7. Caroline says:

    You’re right, that does fol­low a pat­tern! Both you and Maryanne are find­ing cre­ative solu­tions, which is good exer­cise for your brain! I think it says that your frontal lobes are in good shape — good work!

  8. Randy says:

    This clue con­fused me:

    If you do your fig­ures from east to west,

    wouldn’t that mean from right to left?

  9. Caroline says:

    Good­ness Randy — you’re right! I’ll change it now!

  10. joseph knecht says:

    An alter­nate solu­tion, since the prob­lem doesn’t state that the num­bers must be inte­gers:

    If the first num­ber is greater than the sec­ond num­ber, add them and then sub­tract the dif­fer­ence of the first and sec­ond num­ber. This cov­ers row 1 and row 3.

    If the first num­ber is less than the sec­ond num­ber, then add them and then sub­tract one less than the dif­fer­ence. This cov­ers row 2, and indi­cates 2.5 as a solu­tion to row 4.

  11. Caroline says:


    Inter­est­ing solu­tion, but if you don’t know what the first num­ber in line 4 is, how do you know which rule to fol­low (the rule for lines 1 & 3 or the rule for line 2)?

  12. joseph knecht says:


    Luck­i­ly for me, there was no solu­tion where the first num­ber is greater than the sec­ond num­ber.

  13. Caroline says:


    You’re right. The solu­tion for the first num­ber being larg­er doesn’t make sense (I end up with 16=4). If the first num­ber is small­er, it does work out, but I get 1.5 as an answer.

    Nice solu­tion! Com­pli­cat­ed, but it works!

  14. joseph knecht says:


    Right you are! Thanks for the cor­rec­tion.

  15. john says:

    ? whats next

  16. Alvaro says:



    good one!

  17. Michael says:

    i found a dif­fer­ent solu­tion
    7*4=2 8
    3*9=2 7
    6*5=3 0, the impor­tant dig­it is only the last dig­it there­fore
    3*8=2 4, now 6 may have worked but each pair has an odd and an even num­ber plus no pair is dou­ble dig­it.

  18. Caroline says:

    Cre­ative Michael! Fol­low­ing your rules, I get 3 and 8 as pos­si­ble answers, with­out a way to choose one answer. In line 2, both 3 and 9 are odd, so keep­ing it even and odd in each line doesn’t work. If you can come up with anoth­er rule to make only one answer, it’ll work!

  19. I didn’t get the cor­rect answer. I got five. the way I came to this was by adding the first and third num­ber in each row. then you take that answer and sub­tract 1 from the num­ber in the “one’s” spot. excuse my lack of knowl­edge. the num­ber 123 1 is the hun­dreds, 2 is the tens, and 3 is the ones. so sub­tract 1 from the ones place and I came to the answer 5.

  20. icanrule says:

    I came up with 3 but I got it in a dif­fer­ent man­ner. Here is the way I fig­ured it out.

    1. 7 x 4 = 28 and Sub­tract first num­ber = 8
    2. 3 x 9 = 27 and sub­tract the first num­ber = 7.
    3. 6 x 5 = 30 and sub­tract first num­ber but since num­ber can’t be zero make it 10.
    4. 3 x 8 = 24 and sub­tract the first num­ber = 4.

    Although the 3rd rule doesn’t jive all that well it still works.

  21. MomV says:

    Pat­tern Recog­ni­tion …C is the answer I picked.

  22. dunc says:

    i came up with

    (7×4)-20 = 8

    (3×9)-20 = 7

    (5x6)-20 = 10

    (3x8)-20 = 4

    go fig­ure..

  23. Alvaro says:

    Hel­lo Erin, I wish you the best in 2008, per­haps includ­ing a more will­ing atti­tude to take on chal­lenges and, if you decide not to give it a try, not to insult oth­er peo­ple in that defen­sive, unhelp­ful way. No one is per­fect 🙂

    Have a great hol­i­day and we hope to see you around again.

  24. Ines says:

    I thought the exact same way as Michael, and icansure:

    1. 7 x 4 = 28 and Sub­tract first num­ber = 8
    2. 3 x 9 = 27 and sub­tract the first num­ber = 7.
    3. 6 x 5 = 30 and sub­tract first num­ber but since num­ber can’t be zero make it 10.
    4. 3 x 8 = 24 and sub­tract the first num­ber = 4.

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