If you find Speed Maths interesting, you'll probably want to check out Trachtenberg's "Speed System of Basic Mathematics" book: http://www.amazon.com/Trachtenb

If you find Speed Maths interesting, you'll probably want to check out Trachtenberg's "Speed System of Basic Mathematics" book: http://www.amazon.com/Trachtenberg-Speed-System-Basic-Mathematics/dp/4871877094 http://www.amazon.com/Trachtenberg-Speed-System-Basic-Mathem...