Hilary Koll worked as a math teacher in an elementary school and also lectured in Mathematics at the University of Reading, England. More recently, she has turned her attention towards publishing and is now a full-time writer and consultant in Math Education. In conjunction with Steve Mills she has written over 150 titles for a variety of publishers, including Letts, Heinemann and QEB. Steve Mills was a teacher in both elementary and high school before lecturing in Math Education at the University of Reading, England. During this time he began to write math books for both teachers and children and in conjunction with Hilary Koll, has written over 150 books.