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I wonder what we can find out about the areas of shapes drawn on dotty grids...
This video might give you some ideas.
Play with the interactive environment below, or print out some dotty paper.
Full Screen tablet/mobile friendly version
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.