Grandpa and Noah are sitting on a bench in a square that keeps getting smaller every day. The square is strange but also familiar, full of the odds and ends that have made up their lives: Grandpa's work desk, the stuffed dragon that Grandpa once gave to Noah, the sweet-smelling hyacinths that Grandma loved to grow in her garden. As they wait together on the bench, they tell jokes and discuss their shared love of mathematics. Grandpa recalls what it...