This book includes all 300 problems from the ten Junior Mathematical Challenge papers set by the UKMT between 2007 and 2016. The problems-which are not given as multiple-choice questions-have been grouped together in two ways: by difficulty; and by topic. The answer to every problem in the book is included. Also,nearly every problem has a remark of some sort. Each remark is not intended to be a 'full written solution', but sketches one method, providing a sequence of pointers so that, hopefully, the reader is then able to go on and solve the problem.