This is a short book about an approach I have developed for the teaching of maths in a play based classroom. This approach has its roots in the Mantle of the Expert approach. Using this approach children are posed as experts, helping clients that come to them with their problems. They work in an agency to defeat 'villains' like subtraction shark, the doubling dinosaur and the knight adder. As part of the agency they undergo regular professional development to ensure they have the skills to defeat these villains. This approach has transformed my maths teaching and taken number sense and number confidence to a new level. This book will give you all the ideas you will need to set up your own agency. I am frequently adding bits and pieces to my store which I use in agency. Find out more at numberagents.blogspot.com.