Can you determine what goes in place of the question mark?

## SUNDAY PUZZLE #34: Complete The Series

I don’t feature visual riddles very often, but this one was too good to pass up. It was posed by somebody at my coworking space, and I found it especially clever (if a bit devious). I also appreciate how easy it is to share—it’s the kind of puzzle that’s perfect for scribbling on a bar napkin, or a classroom chalkboard. Your task is simple: Determine what goes in the place of the question mark. And no, the answer is not “6.”

We’ll be back next week with the solution – and a new puzzle! Got a great brainteaser, original or otherwise, that you’d like to see featured? E-mail me with your recommendations. (Be sure to include “Sunday Puzzle” in the subject line.)

## SOLUTION To Sunday Puzzle #33: Pigs In Pens

Last week, I asked you how to distribute 21 pigs into four pigpens, such that each pen contained an odd number of pigs. At first glance, it seemed impossible. Dividing 21 into four groupings requires at least one of those groups to contain an even number of pigs, right?

Well, technically yes. But the puzzle is possible, if you build your pens correctly. As many of you quickly caught on, the solution to this brain teaser hinges on how the pens are built relative to one another. Specifically, it requires that one build a pen *around* another pen (or pens). “One way would be to put 7 pigs in 3 pens each, then build one large pen that encloses the whole 21” wrote cdeck, the first reader to propose a valid solution (and if you check last week’s comments, there are many) using the “nested pens” method. Reader WiessCrack drew a diagram to help visualize this solution:

**Previous Weeks’ Puzzles**

- Can You Solve This Extremely Difficult
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*Contact the author at **rtgonzalez@io9.com**.*

## DISCUSSION

R