Being resourceful

Nine squares with side lengths 1, 4, 7, 8, 9, 10, 14, 15, and 18 cm can be fitted together to form a rectangle. What are the dimensions of the rectangle?

This problem challenges you to work out what fraction of the whole area of these pictures is taken up by various shapes.

Can you order the digits from 1-3 to make a number which is divisible by 3 so when the last digit is removed it becomes a 2-figure number divisible by 2, and so on?

Look at what happens when you take a number, square it and subtract your answer. What kind of number do you get? Can you prove it?

What is the largest 'ribbon square' you can make? And the smallest? How many different squares can you make altogether?

Try out these calculations. Are you surprised by the results?