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The eight queens puzzle
Place eight queens so that no two attack each other: none sharing a rank, file, or diagonal. Many...
Sorting the pieces
Sorting is the first act of mathematics: choose a property, then group by it. The pieces can be...
Wie viele Quadrate stecken im Brett
Zähle Quadrate jeder Grösse, nicht nur die 64 Einheitsfelder. Ein k times k-Quadrat hat (9-k)...
Each square has a name
The board is a coordinate grid. The eight columns are files , labelled a to h from White's left....
The colour of a square from its coordinates
Every square is light or dark, and you can tell which without looking at a board. Number the files...
The pigeonhole principle
The pigeonhole principle says that if you place more items than boxes, some box holds at least two...
How many squares on the board
Count every square of every size on the board, not just the 64 unit squares. A k times k square can...
Counting routes with Pascal
A counter starts at the bottom-left and moves only up or right. How many shortest routes reach each...
Sprünge eines Königs zählen
Ein König kann auf jedes Nachbarfeld treten, das auf dem Brett bleibt. Zählt man, wo er nach einer...
Wheat on the chessboard
The legend puts 1 grain on the first square, 2 on the second, 4 on the third, doubling each time....
Slope reasoning on paper
This is the pencil-and-paper form of the no-three-in-line problem, placing 11 counters on the 8...
Zwölf Springer bewachen das Brett
Wie wenige Springer greifen jedes freie Feld an? Dieses Minimum ist die Dominationszahl des...