Touch Press recently announced its newest title, Incredible Numbers, by Ian Stewart. The rich interactive explorations in the ebook were prototyped in the Wolfram Language by Phil Ramsden, who is a Teaching Fellow at Imperial College London and a Mathematica trainer. We asked him to relate his experience here. Ian Stewart's mathematical imagination is boundless. There are few areas of the subject that haven't been illuminated, for a general readership, by his gift for clear and vivid exposition. So when Ian, Touch Press, and Profile Books decided to create something interactive, they needed a development and prototyping environment in which you can do pretty much anything; a mere specialist application wasn’t going to cut it. That's where the Wolfram Language came in and, happily for me, where I did too. The Wolfram Language provides an environment in which you can do pretty much anything, and do it quickly. The reason that the Wolfram Language is such a “game-changer” is that where interactive content is concerned, it takes us into a world where an idea (such as one of Ian’s) can become a working prototype in no time.