This riddle was adapted from a mathematical exercise presented in The Moscow Puzzles: 359 Mathematical Recreations by Boris Kordemsky. The original puzzle consisted of an arrangement of rabbits in two square cages, one stacked atop the other, with one chamber in the center of each cage reserved for equipment. Of course, the solution is the same as that of our human cannonball riddle, though the stakes aren’t quite as high.

Does this puzzle remind you of a certain beloved pastime? You might have noticed some similarities to Sudoku, which also requires solvers to apply logic to a combinatorial number-placement puzzle. These types of recreational mathematic games have a long history in popular entertainment, with early “magic square” examples appearing in 19^th century French newspapers—for example, this puzzle featured in Le Siècle in 1892. Kordemsky essentially created a stacked version of this type of problem (think 3D chess from Star Trek), using a visual aid (rabbits) as a stand-in for numerical values. Its complexity belies its true simplicity, which characterizes much of The Moscow Puzzles and, we hope, our Human Cannonball riddle.

Want more puzzles? TED-Ed has lots of fun and challenging brainteasers in our Riddle Series!

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