We may be celebrating Pi Day here at io9, but we would be irrational to deny that there’s more to mathematical interestingness than simply dividing an object’s circumference by its diameter. Here are seven numbers we love as much as pi.

There are similarities in the way a bird flies through the air and a dolphin swims through the water. And yet how do you compare the flap of a butterfly to the enormous movement of a blue whale? The best way, it turns out, is with their respective Strouhal Numbers.

Ships are 'she,' people have motherlands and fatherlands, but what about a picture of a baby with the number '1' on it? What about a nice beef stew? Or a chair? Strangely, we tend to assign genders to all of them in a fairly predictable way.

This week, we're gearing up for 9, Shane Acker's film about nine animated rag dolls, each known only by their number. With that in mind, we list 16 other characters who have numerical monikers.