This weekās puzzle is not about gravity, though youād be excused for suspecting as much. After all, when most people read āIsaac Newtonā and ātreeā in the same sentence, they think also of falling apples. But this weekās puzzle, which is widely attributed to Newton, is actually an exercise in orderly arboriculture.

### Sunday Puzzles #42: Newtonās Trees

Tree-planting puzzles, which are also known as āpoints and linesā puzzles, āhave 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 Newtonās tree-planting puzzle, which he calls āthe 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? *

Weāll be back next week with the solutionāand a new puzzle! Got a great brainteaser, original or otherwise, that youād like to see featured? E-mail me with your recommendations. (Be sure to include āSunday 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 weekās 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 2ās cigar-placements from thereon out. Gawker Mediaās 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 Newtonās apple tree, at Trinity College, Cambridge. Credit: Fernando Mandujano | CC BY-NC-SA 2.0.*