You could remember it this way: "A pizza is a circle, and the area of a circle increases with the square of the radius." Or in a much simpler way: Always buy the bigger pizza. So declares Quoctrung Bui at NPR's Planet Money blog, whose post on the comparative values of pizzas got quite a bit of attention this week. With geometry and impressive graphics on his side, Bui points out that a 16-inch pizza is four times larger than an 8-inch pizza, even though the price difference doesn't reflect that. So always go big or you're wasting money, he argues.
Unless, of course, you're worried about "negative marginal returns," counters Planet Money colleague Jess Jiang in a separate post. This gets a little more subjective than geometry. "For most people, there's a point at which more pizza makes you less happy," she observes. It might be the hassle of dealing with leftovers, or the sick feeling after scarfing down a few slices in the middle of the night. At io9, Ria Misra is firmly in camp Bui. "But 'I'm not hungry for that much pizza,' you say? Allow me to refute your argument with two simple words: Cold. Pizza."