http://www.amazon.com/Trachtenberg-Speed-System-Basic-Mathematics/dp/0313232008
废话不想多说，速算第一书籍当之无愧，特摘录读者的评论如下

I have read a lot of books on speed mathematics, and without exception, they are all useless except this one. The method described here is easy. But most importantly, it scales up to larger numbers without additional complexity. This scaling up is what differentiates this method from the others.

The key to learning this method is skip the first chapter. Don't waste time in learning how to multiply by 8. Rather, start with the second chapter, the "direct method" for multiplication.

You will surprise your friends and family when they see you multiplying numbers in your head.