As a result of media and parental attention to need for improvement of core skills, this is a fast-paced mental arithmetic book to encourage mastery of two of the four rules of number. It is part of a range of books which "Complete Mastery" and "Superhuman Calculator". The book recommends that children spend 15 minutes each day using this book to compete against themselves or against friends. They do the tests again and again becoming increasingly accurate and beating their own times. Eventually they should be able to do all the sums in 30 seconds and become a "30-second champion"! Children need scrap paper, a watch with a second hand, scrap paper and a calculator.