Have you ever been about to finish a puzzle, when suddenly you realize there are more holes left than you have pieces? With [Nikolaos’s] 3D printed sliding puzzles, this will be a problem of the ...

Jeff Smith is a former Math teacher and a retired US Navy Lieutenant Commander. Reach him at [email protected].

Have you ever been about to finish a puzzle, when suddenly you realize there are more holes left than you have pieces? With [Nikolaos’s] 3D printed sliding puzzles, this will be a problem of the ...

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Test your mettle with this puzzle created exclusively for "Smithsonian" readers Test your mettle with this puzzle created exclusively for 'Smithsonian' readers Test your mettle with this puzzle ...

A Delta Air Lines flight last week was canceled after the flight crew mistakenly deployed an emergency slide before boarding.