Subtraction Explorer: A world of subtraction to discover. Come and join Dr Maths and his team and discover the fun that can be had with the Explorer series of books. There are thirty Quests that have to be undertaken from exploring mines, travelling through deep space, trekking across the Kalahari or finding pirate treasure. These puzzles are fun to do and are a great way to improve maths understanding, map reading and help with overall problem-solving ability. No matter what age you are; from children wanting to improve, to parents wanting to keep up with their children, to grandparents who know the importance of exercising their brain, these books are great fun and good for you. All you need is a pencil and a sense of fun and adventure! So come on and join the team. Make Dr Maths proud!