This book is a collection of number puzzles on which to test your mind and ingenuity. It is also an interesting and thorough introduction to the methods and techniques which can be used to solve them. All the puzzles are in the form of a sequence of numbers with missing terms. For each of them there is an underlying rule or hidden connection between the numbers and you have to spot what it could be. When you find the rule, it will explain how the sequence was generated and so make it possible to calculate the missing term or terms. The fascination of puzzles like these, as with so many aspects of mathematics, lies in the combination of logical thinking and sudden bursts of inspiration. There is no single way to solve them but by working through the twelve different types given in this book, you will have gained a valuable insight into suitable methods to try. To reinforce that insight, at the end of each set of examples there is a collection of five puzzles of that type for you to solve yourself. The final chapter offers five collections of fifteen randomly mixed puzzles, so you will then be able to test your skill and ingenuity to the full. Having mastered them you will be well-placed to solve the number puzzles which are so popular in newspapers, magazines and competitions.