Mathematics: A Basic Introduction: Teach Yourself by Alan Graham
The book covers all the basic areas of mathematics including calculating, fractions, decimals, percentages, measuring, graphs and formulae.
Everything you will need is here in this one book. Each chapter includes not only an explanation of the knowledge and skills you need, but also worked examples and test questions. At the end of the book a series of challenges and games provide new and interesting ways to apply your new skills.