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In this game, two players take it in turns to click on a dot on the grid.
The winner is the first to have four vertices of a square in their colour.
Play a few games against the computer or a friend.
Full Screen and Mobile Version
Can you develop any winning strategies?
Can you suggest any mathematically interesting variations on the game?
You may be interested in the other problems in our Exploring mathematics on dotty grids Feature.
Five numbers added together in pairs produce: 0, 2, 4, 4, 6, 8, 9, 11, 13, 15 What are the five numbers?
15 = 7 + 8 and 10 = 1 + 2 + 3 + 4. Can you say which numbers can be expressed as the sum of two or more consecutive integers?
Three people chose this as a favourite problem. It is the sort of problem that needs thinking time - but once the connection is made it gives access to many similar ideas.