Published in association with the Turing Trust, this challenging collection of number crunch puzzles will really put your numerical skills to the test.Follow in the footsteps of famous World War II codebreaker Alan Turing who used impeccable logic to decipher the military codes used by Germany and its allies. These expert puzzles offer a tough but enjoyable metal work-out, with puzzles in three levels of difficulty. Starting at the top with the number provided, your challenge is work downwards from one box to another, applying the mathematical instructions to your running total until you reach a final answer. You can write the answer to each step down, or to really stretch yourself, keep the running total in your head, which is easier said than done!This book includes a foreword written by Sir Dermot Turing, nephew of Alan Turing and trustee of the former British codebreaking HQ, Bletchley Park. Sales of these books support the work of The Turing Trust, a charity set up by Alan Turing´s family which provides much needed computers to schools in Africa.