A simple and very concise/quick introduction to various simple math techniques originally developed in India. Likely, these have been dealt with at length in Vedic Math type of books, but this is a very inviting quick read.
For contents, head out to Google Books:
This book taps the mathematical traditions of India for some simple and elegant methods of performing arithmetic calculations. There are techniques for multiplication, division, squaring, square-rooting and factorisation that, once mastered, are faster than the conventional approaches currently in wide use. Errors arising out of carelessness in calculation were apparently a problem faced by our ancestors too! They devised an amazingly simple technique to catch such errors. These techniques are presented in this book in a lucid manner, with a large number of examples to illustrate the basic ideas and elaborate on their variations. The use of Sanskrit terms has been minimised. Most of the methods described are general and work for all numbers, not just for special cases. The mixed-number, or Mishrank, which contains both positive and negative digits, is extremely useful in simplifying calculations and is widely used in this book. The reader will find that ideas such as these can be effectively grafted to the conventional methods. The book will interest a wide audience. Students will benefit the most, since they can easily make the methods of this book their own. They will soon find that much of their arithmetic can be performed orally. Adults will find it a pleasure to discover new and elegant ways of doing things they already know. The computer enthusiast may find hidden in the simple methods ideas to speed-up machine computation. Finally, the mathematically-inclined may find their curiosity sufficiently aroused to go beyond this book and delve deeper into the Indian mathematical legacy.