My answer is P. But I am not sure as there is not sufficient data to support this.

B(2), ____, G(7), ____, L(12), _____ (alternating sequence of difference 5: 2, 7, 12, 17,...)

____, D(4), ____, J(10), ____, P(16) (alternating sequence of difference 6: 4, 10, 16, ...)

Is this correct answer? Or can someone come up with different answer with better logic?

  • 1
    $\begingroup$ Welcome to Puzzling.SE! Where did you get this puzzle from? If it's not a puzzle you created yourself, you need to credit the original source, otherwise it can be considered plagiarism. $\endgroup$
    – F1Krazy
    Oct 25, 2023 at 16:51
  • 2
    $\begingroup$ My friend sent it to me. He was asked in an in-person interview for the trader role. $\endgroup$ Oct 25, 2023 at 16:53
  • $\begingroup$ I think 2 datapoints for the even-indexed letters is not enough to support your idea. That said, this is a pretty short sequence $\endgroup$ Oct 25, 2023 at 21:53
  • $\begingroup$ If it's an interview question it might be purposefully designed not to have an obvious answer, to get an idea about how the candidate is thinking an exploring options. $\endgroup$ Oct 26, 2023 at 5:45

5 Answers 5


Maybe the answer is



the sequence consists of every other consonant starting with B:

(a) B C D (e) F G H (i) J K L M N (o) P Q R S ….


I think the next letter could be


As these are

The "voiced" consonants (consonants which require the use of vocal cords) in alphabetical order.




I agree strongly with the comments and the trend of the answers so far: This is likely a question without a clear answer that was asked to try to learn something about the interview candidate's thinking/pattern recognition processes. The pattern isn't simple enough to confidently identify a single answer. If it had been every 3rd letter, B,E,H,K,N,__ for instance, then while other patterns could definitely be identified, the obvious answer would be Q.

This pattern isn't that simple, and I can't see how any of the solutions given are better or worse than the others.

My solution (I will suggest that as an interviewer I would not be thrilled with this as anything other than an initial observation.): M

I noticed that the patterns of skipped letters is 1 - 2 - 2 - 1. This could repeat.
B (skip 1) D (skip 2) G (skip 2) J (skip 1) L (skip 1) M

Again, not a clever pattern and not well supported by the available data - I just felt that I should include my own solution to the problem rather than a just commentary about the questioner's reasoning.

  • 1
    $\begingroup$ Why would the pattern repeat every 4 steps when the simpler option of repeating every 3 steps is also possible? $\endgroup$ Oct 26, 2023 at 11:27
  • $\begingroup$ That's just another of the many options. Actually, 1-2-2-1-1-2-2-1 looks prettier to me than 1-2-2-1-2-2. $\endgroup$
    – Florian F
    Oct 26, 2023 at 11:28
  • $\begingroup$ @JaapScherphuis That's kind of the point. You saw the 1 as the new beginning of a repeating cycle while I saw it as the end of a symmetric cycle. $\endgroup$ Oct 28, 2023 at 12:43

It could be O

Convert to integers, 2, 4, 7, 10, 13.
deltas are: 2, 3, 3, 2.
continue pattern 2, 3, 3, 2, 3, 3 -> letter L+3 = O

Or it could be N

deltas are: 2, 3, 3, 2.
continue with doubles 2, 3, 3, 2, 2, 3, 3, 2 => letter L+2 = N

Or maybe L

deltas are: 2, 3, 3, 2,
2nd deltas are: 1, 0, -1.
continue 1, 0, -1, -2, deltas are 2, 3, 3, 2, 0 => letter L+0 = L

Or maybe O after all

deltas are: 2, 3, 3, 2,
follow Morse-Thue pattern 2332322332232332... => letter L+3 = O

Or it could be P

There are two interleaved sequences:
B, G, L: progression 5
D, J, ?: progression 6 => letter J+6 = P

As infinitezero and Jason Patterson suggest, the question is not to find the correct answer but to see how you think.


I think it is M or N or O. Reasons below. (BTW my reasoning might be weird and difficult to understand).



My way of doing it is kind of using math here. The number is equivalent to the amount of letters that space the "other letters". Says B to D. D is two letter after B. So using this logic:

B+2=D D+3=G G+3=J J+2=L

So to solve this, i need to follow the pattern. Before B was A, so A+1=B. So I think the pattern is. x+1, x+2, x+3, x+3, x+2, x+1.

With that reasoning of the (+1), the answer is M. If you go:

x+2, x+3, x+3, x+2, x+2, then the answer is N.

If you go:

x+2, x+3, x+3, x+2, x+3. Then the answer is O.

As I said before, my reasoning might not be understandable, I understand.


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.