This weekās puzzle is not about gravity, though youād be excused for suspecting as much. After all, when most people read āIsaac Newtonā and ātreeā in the same sentence, they think also of falling apples. But this weekās puzzle, which is widely attributed to Newton, is actually an exercise in orderly arboriculture.

### Sunday Puzzles #42: Newtonās Trees

Tree-planting puzzles, which are also known as āpoints and linesā puzzles, āhave always been a matter of great perplexity,ā English author and mathematician Henry Ernest Dudeney wrote in in his 1917 collection of puzzles, Amusments in Mathematics. In that text, he refers to Sir Isaac Newtonās tree-planting puzzle, which he calls āthe most familiar exampleā of this genus of brain-teaser. I have restated it briefly, below:

How can nine trees be arranged in ten rows, such that each row contains exactly three trees?

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Weāll be back next week with the solutionāand a new puzzle! Got a great brainteaser, original or otherwise, that youād like to see featured? E-mail me with your recommendations. (Be sure to include āSunday Puzzleā in the subject line.)

### SOLUTION to Sunday Puzzle #41: Dueling Cigars

Last week, I described a game in which two players alternate placing cigars on a tabletop. The rules of the game state the last player to to place a cigar on the table wins. The puzzle: Given certain stipulations about the size of the table and the placement of the cigars, one of the players should win every time. Which player is it, and why?

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There is a very elegant solution to this puzzle, which many of you identified it in last weekās comments. I believe the first commenter to describe it was DL Thurston. A few minutes later, DarthClem3 and some other comments worked through the solution and arrived at an even more thorough answer over the course of this thread. The solution is this: The secret to winning this game every time is to 1) Be the first player to place a cigar; 2) Place your first cigar at the exact center of the table, standing upright; and 3) Mirror each of player 2ās cigar-placements from thereon out. Gawker Mediaās Art Director, Jim Cooke, put together a little animation to help visualize this process:

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Contact the author at rtgonzalez@io9.com and @rtg0nzalez. Top photo: A reputed descendent of Newtonās apple tree, at Trinity College, Cambridge. Credit: Fernando Mandujano | CC BY-NC-SA 2.0.