I have an IQ question which is giving me a very hard to time to figure out. Please help me find the answer with an explanation.

It seems so simple...

enter image description here

  • $\begingroup$ puzzling.stackexchange.com/questions/6490/… says "the question is bad; sequence questions generally are." Same with this. Here's a solution: we are writing the numbers in base 12 and mark them with red if they are prime. The sequence we are writing is 1, 13, 145, 1728. So it's D. Why these numbers? See the already linked answer, any sequence can be generated so. An even simpler solution would be F: we just repeat the same pattern in the first five pictures. $\endgroup$
    – chx
    Commented Apr 23, 2017 at 9:36

1 Answer 1


It will be


You can kind of see how it is going. Here is the next two (hollow dots):

enter image description here

It goes

One right, one right diagonal, creating a 45 degree angle.

Here is an extended version:

enter image description here

A more detailed explanation based on elimination:

First you can see that it goes


So it becomes apparent that Red gets two turns of being added, then blue. So now it will be red, ruling out A, D and F.

Next we can see that the new dot is always added somewhere to the right, ruling out E.

So B and C are left. The last thing to note is that the first time a new coloured dot is added, so
B R R B B (R)

the new dot it is always added to the bottom right. So that rules out B giving C. The dot after will be added to the diagonal right, one up and one across from the previous highest dot

  • $\begingroup$ @Mordechai :P well it's not exactly the best drawing anyway $\endgroup$ Commented Apr 23, 2017 at 7:30

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