When is a group a union of 3 proper subgroups?
What the shape: A dangling rope.
Reassembling a cube.
Rolling a coin around other coins.
Pairing points with disjoint line segments.
Maximal rooks and bishops.
Godly magic squares.
General position in chess: No-three-in-line problem.
Guessing a natural polynomial.
Frodo's number.
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