Click here to win prizes by solving the puzzle Advent calendar.
Click here to win prizes by solving the puzzle Advent calendar.



One two three

Each point on a straight line is either red or blue. Show that it's always possible to find three points of the same color in which one is the midpoint of the other two.

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Tags: colouring
If you enjoyed this puzzle, check out Sunday Afternoon Maths XLIII,
puzzles about colouring, or a random puzzle.


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