These squares have been made from Cuisenaire rods. Can you describe
the pattern? What would the next square look like?
Cut differently-sized square corners from a square piece of paper
to make boxes without lids. Do they all have the same volume?
Can you use this information to work out Charlie's house number?
This famous puzzle requires you to use the information to limit
your search. We know when De Morgan died, so when he was born
wasn't hundreds of years before, was it?! That helps you think
about what would be reasonable for $x$ and $x^2$.
Why not try an age and see what happens?
Remember that $x^2$ means $x \times x$.