This game for two players comes from Ghana. However, stones that were marked for this game in the third century AD have been found near Hadrian's Wall in Northern England.
Some puzzles requiring no knowledge of knot theory, just a careful
inspection of the patterns. A glimpse of the classification of
knots and a little about prime knots, crossing numbers and knot
Investigations based on an Indian game.
Fifteen is a game for two players that you can play anywhere,
anytime. Try it without writing anything down. You take it in turns
to choose one of the whole numbers 1 to 9 (and each number can only
be chosen once). To win you have to pick 3 numbers that add up to
Can you beat the computer?
Can you analyse the structure in the following games and the
correspondences between them? Describe the patterns that show they
are equivalent games that can be played using equivalent
We suggest tackling them in the order given.