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## 'Exploring Diagonals' printed from http://nrich.maths.org/

Move the top right-hand corner of the rectangle.

Can you work out what the purple number represents?

What would be the dimensions of a rectangle with a purple number of 24? Is there more than one?

If I tell you the coordinates, can you find a quick way to work out the purple number?

What other interesting questions might you explore?