# IQ test question: matrix of numbers

For this matrix I came up with 12 (which isn't an option) and can't see other answers. Which choice is it?

1 2 4
2 4 7
4 7
• 1
• 11
• 13
• 8
• 6
• 14
• This is not a very good IQ test question since there are many possible answers that are equally valid. They could be tribonacci numbers, lazy caterer sequence, or Fibonacci numbers minus one. Or any one of several sequences containing 1,2,4,7. Commented Jun 23, 2018 at 5:00
• Maybe the answer is "secret hidden answer #7: "All of the above." Commented Jun 23, 2018 at 16:38

## 5 Answers

The answer is:

11

Because

Any given diagonal contains the same number. You can get from one diagonal to the next by adding an incrementing number - +1, +2, +3 or +4 (1+1 → 2+2 → 4+3 → 7+4 → 11)

• Plot twist... my solution is the actual one. I just tried to prove it lmao. Commented Jun 24, 2018 at 0:15
• And like Riley said, it doesn't necessarily mean an incrementing number. It could be tribonacci, thus 13 Commented Jun 24, 2018 at 0:16
• I thought of 11 this way: Ignore the matrix and think of the numbers in one row; 1, 2, 4, 7, 11. It's simply +1, +2, +3, +4! And then the matrix is just going through each triplet. Point being, this is a pretty bad IQ question since not only do you have multiple answers, you have multiple ways of getting to the same answer, which isn't useful for a question testing IQ. Commented Jun 24, 2018 at 10:47

11. Column 2 = Column 1 + {1,2,3}. Column 3 = Column 2 + {2,3,4}.

The solution is pretty simple.

All numbers stay the same in diagonals (obvious). To find numbers in the third column, we simply take the sum of the two other columns in a given row and the value of the cell in the row above in the first column. Thus, 2+4+7=13. :)

EDIT

As Riley informed me... Its better to look at this as tribonacci numbers. In effect, we take the sum of each number in a row and that is equal to that of the third column in the row below...

• Both of your solutions are trying to generalise based on a single observation (f(X) = Y, f(Z) = ?), which may be technically correct, but seems unlikely to be the solution the question creator had in mind. Commented Jun 23, 2018 at 8:24

If there has to be 1 answer the answer is 1. It's a trick question, where you all start counting and come to different outcomes. The conclusion is that you shouldn't.

You have to imagine 4 boxes with the numbers 1247 as the numbers move up in the columns you take the top one back down to the bottom.

Well, I guess the answer is

1

As,

With 1, we get a symmetrical matrix, the symmetry is being formed by the main diagonal from top left to bottom right (1,4,1)

• Very funny, ha-ha. Could you please name a number (any number at all, no need to limit yourself to the given options) that could be substituted for the question mark so that the result would not be a symmetric matrix?
– Bass
Commented Jun 23, 2018 at 20:13
• This confirms to Riley's comment. So 1 is just an example. It can be any number for that sake. Commented Jun 24, 2018 at 6:21