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Two standard methods for working out the areas of shapes may help.
Boxing in the tilted squares, working out the area of the box and subtracting the areas of the unwanted right-angled triangles:
Splitting the tilted squares into right-angled triangles and squares and adding the areas of the different parts:
Can you explain the strategy for winning this game with any target?
Is there an efficient way to work out how many factors a large number has?
Draw a square. A second square of the same size slides around the first always maintaining contact and keeping the same orientation. How far does the dot travel?