A colleague of ours went for lunch at the local Pizza Restaurant.
She ordered a 12-inch pizza, but when the order arrived she received two 8-inch pizzas. The server said that the had run out of 12-inch pizzas with her requested topping, so the kitchen had cooked the 8-inch pizzas instead. And what's more, the restaurant would charge her the price of the 12-inch pizza.
What would you have done?
Obviously someone thought that two 8-inch pizzas was more than a single 12-inch pizza - two times eight is 16, which is more than twelve!
However, the area of a pizza (or anything circular come to that) is proportional to the square of its radius.
In this case an 8-inch pizza, with a radius of four inches, has an area of 16 x Pi. And two will have a combined area of 32 x Pi.
On the other hand, a 12-inch pizza, with a radius of six inches, has an area of 36 x Pi. Which is less than the two 8-inch pizzas.
So this is not a good deal.