Choose some fractions and add them together. Can you get close to 1?
Can you find triangles on a 9-point circle? Can you work out their angles?
Draw some quadrilaterals on a 9-point circle and work out the angles. Is there a theorem?
The answer is $5x+8y$... What was the question?
Explore the relationships between different paper sizes.
Find the sum of this series of surds.