30 years ago Colin Runciman asked What About the Natural Numbers? Now, in 2019, we find ourselves in need of a successor to carry Runciman's banner. Despite major advances in type systems and the growing adoption of the slogan 'make illegal states unrepresentable', we often rely on Integers in cases where negative values have no meaning. Runciman's paper reminds us of a fact that we all know: the choice in types can change the nature of an API. Integers are often the default in many systems and APIs, often for no reason beyond programmer familiarity. In this talk we will argue two main points: that for many cases Natural numbers retain all of the positive aspects of the Integers with none of the negatives, and that when designing a system or an API we should constantly be asking ourselves "What about X?"