Copyright © University of Cambridge. All rights reserved.
'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?