April 20, 2010

Solve 2 3 4 15 12 3 4 5 28 20 4 5 6 45 30 5 6 7 66 42 6 7 8 ? 56



Find the missing number ?

2 . 3 . 4 . 15 . 12
3 . 4 . 5 . 28 . 20
4 . 5 . 6 . 45 . 30
5 . 6 . 7 . 66 . 42
6 . 7 . 8 . ?? . 56

30 comments:

  1. karthikApril 20, 2010 at 4:33 PM

    91 is the missing number
    4*3+3*1=15
    5*4+4*2=28
    6*5+5*3=45
    7*6+6*4=66
    8*7+7*5=91

    ReplyDelete
  2. Kris LuciusApril 21, 2010 at 9:10 PM

    This comment has been removed by the author.

    ReplyDelete
  3. Kris LuciusApril 21, 2010 at 9:11 PM

    I also got 91 but through a different, but similar, method (i utilize the first four columns of numbers only):

    2+ 3*4 + 1 =15
    3+ 4*5 + (1)+4 =28
    4+ 5*6 + (5)+6 =45
    5+ 6*7 + (11)+8 =66
    6+ 7*8 + (19)+10 =91

    ReplyDelete
  4. Kris LuciusApril 21, 2010 at 9:23 PM

    Karthik's is more elegant, darn it

    ReplyDelete
  5. UnknownApril 22, 2010 at 2:02 PM

    2 . 3 . 4 . 3*5=15 . 3*4=12
    3 . 4 . 5 . 4*7=28 . 4*5=20
    4 . 5 . 6 . 5*9=45 . 5*6=30
    5 . 6 . 7 . 6*11=66. 6*7=42
    6 . 7 . 8 . 7*13=91. 7*8=56

    ReplyDelete
  6. aquasanApril 24, 2010 at 1:54 AM

    This comment has been removed by the author.

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  7. aquasanApril 24, 2010 at 1:55 AM

    This comment has been removed by the author.

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  8. OccumApril 29, 2010 at 5:42 AM

    I agree with Kuresh. The math is there.
    R.

    ReplyDelete
  9. UnknownApril 29, 2010 at 12:41 PM

    A B C((B*C)+(B*(A -1)))(B*C)
    2 3 4 ( 12 + 3 *1) 12
    3 4 5 (20 + 4 * 2) 20
    4 5 6 (30 + 5 * 3) 30
    5 6 7 (42 + 6 * 4 ) 42
    6 7 8 (56 + 7 * 5 ) 56


    I arrived 91

    ReplyDelete
  10. PratapMay 23, 2010 at 10:53 PM

    I too got 91.

    A B C ((A+B)*(C-1)) (B*C)
    2 3 4 15 12
    .
    .
    .
    .
    6 7 8 ((6+7)*7=91)

    ReplyDelete
  11. UnknownMay 27, 2010 at 3:45 PM

    91 is the answer

    ReplyDelete
  12. UnknownMay 31, 2010 at 2:27 AM

    I got the same but through different method,
    (first number +third number - 1) * second number
    (2+4-1)*3=15
    (3+5-1)*4=28
    (4+6-1)*5=45
    (5+7-1)*6=66
    (6+8-1)*7=91

    ReplyDelete
  13. Active KingMay 31, 2010 at 11:46 AM

    I too got 91..
    col 3 col 4
    (4*3) +3 = 15
    (5*5) +3 = 28
    .
    .
    .
    .
    (8*11) +3 = 91

    ReplyDelete
  14. ÓlafurJune 7, 2010 at 9:05 PM

    This comment has been removed by the author.

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  15. ÓlafurJune 8, 2010 at 2:20 PM

    A B C D E
    D=((A+B)*C)-(A+B))
    E=B*C

    Value of E is immaterial and the missing D=91

    ReplyDelete
  16. AnonymousAugust 28, 2010 at 9:59 AM

    I went a completely different way but still got 91.

    Pattern in column 1 is +1
    pattern in column 2 is also +1
    Column 3 starts at +13, adding an extra 4 per row.
    eg. 15+13 = 28
    28+13+4=45
    45+13+4+4=66
    66+13+4+4=91

    ReplyDelete
  17. AnonymousSeptember 6, 2010 at 9:20 AM

    91

    ReplyDelete
  18. AnonymousDecember 9, 2011 at 7:40 AM

    91

    ReplyDelete
  19. AnonymousApril 5, 2012 at 2:44 PM

    (a + b) * b
    (6 + 7) * 7 = 91

    ReplyDelete
  20. yuvrajAugust 5, 2012 at 12:13 PM

    in 4 th row ..see the diff between numbers
    28-15=13
    45-28=17
    66-45=21
    ??-66=25

    ans.91

    ReplyDelete
  21. yuvrajAugust 5, 2012 at 12:14 PM

    in 4 th column ..see the diff between numbers
    28-15=13
    45-28=17
    66-45=21
    ??-66=25

    ans.91

    ReplyDelete
  22. HrishiSeptember 21, 2012 at 9:42 PM

    91

    ReplyDelete
  23. Jeevan PatilAugust 1, 2014 at 11:03 PM

    ((2+3)*(4-1))=15
    ((3+4)*(5-1))=28
    ((4+5)*(6-1))=45
    ((5+6)*(7-1))=66
    ((6+7)*(8-1))=91

    ReplyDelete
  24. jeevanrocks19@gmail.comAugust 1, 2014 at 11:08 PM

    ((2+3)*(4-1))=15
    ((3+4)*(5-1))=28
    ((4+5)*(6-1))=45
    ((5+6)*(7-1))=66
    ((6+7)*(8-1))=91

    ReplyDelete
  25. jeevanrocks19@gmail.comAugust 1, 2014 at 11:08 PM

    ((2+3)*(4-1))=15
    ((3+4)*(5-1))=28
    ((4+5)*(6-1))=45
    ((5+6)*(7-1))=66
    ((6+7)*(8-1))=91

    ReplyDelete
  26. jeevanrocks19@gmail.comAugust 1, 2014 at 11:08 PM

    ((2+3)*(4-1))=15
    ((3+4)*(5-1))=28
    ((4+5)*(6-1))=45
    ((5+6)*(7-1))=66
    ((6+7)*(8-1))=91

    ReplyDelete
  27. jeevanrocks19@gmail.comAugust 1, 2014 at 11:08 PM

    ((2+3)*(4-1))=15
    ((3+4)*(5-1))=28
    ((4+5)*(6-1))=45
    ((5+6)*(7-1))=66
    ((6+7)*(8-1))=91

    ReplyDelete
  28. jeevanrocks19@gmail.comAugust 1, 2014 at 11:08 PM

    ((2+3)*(4-1))=15
    ((3+4)*(5-1))=28
    ((4+5)*(6-1))=45
    ((5+6)*(7-1))=66
    ((6+7)*(8-1))=91

    ReplyDelete
  29. AnonymousDecember 11, 2014 at 4:15 AM

    Was I the only one who used fractions?

    The last colum going down, ratios are:
    12/20 => 20 = 12 + 8 = (1+2/3)*12
    20/30 => 30 = 20 +10 = (1+2/4)*20
    30/42 => 42 = 30 +12 = (1+2/5)*30
    ... = (1+2/6)*42
    This gave me the idea for the diaganol.
    ratios:
    12/28 => 28 = (2 + 1/3)*12
    20/45 => 45 = (2 + 1/4)*20
    ... = (2 + 1/5)
    ... = (2 + 1/6)*42
    = 84 + 7 = 91

    ReplyDelete
  30. UnknownAugust 4, 2016 at 6:44 AM

    OK, I'll probably go when I get the answer... but this one is bugging me... the Meme reads "Only For Geniuses" and then gives the following pattern:

    1 + 4 = 5
    2 + 5 = 12
    3 + 6 = 21
    8 + 11 = ?

    The two answers that have been given are 39 and 96

    ReplyDelete