*From the book Get Smart! Maths Concepts, Puffin Books, India, 2008.*I acknowledge the debt I owe to Professor Richard Askey of the University of Wisconsin. Most of the topics of this book are included in a beautiful handout made by Professor Askey. The handout outlines the essential aspects of algebra and geometry that students should know before they learn the Calculus.

I would also like to thank Vatsala Kaul, Penguin’s Editor for this book. Vatsala conceptualised this book creatively, and has clarified the exposition throughout this book. Further, I thank Shubhank Bhadauria and Tarun Sachdeva for creating the graphics in this book.

I thank the following people who are an integral part of my life, and who have encouraged me in one way or the other during the writing of this book: My school friends—Hartosh Singh Bal, Punya Mishra, Poonam Madan, Gaurav Suri, and Vikram Jamalabad. My colleagues— Jagdish Prakash, Shantanu Prakash, Abhinav Dhar, Sangeeta Gulati, and Meena Raju. And my family—Hem Bhatnagar, S. S. Bhatnagar, Saurabh Kumar, Amit Bhatnagar, Jayshree Bhalerao, and Priti Kumar.

Last but not the least, I wish to thank my daughter Tejasi. It is because of Tejasi and her friends that I rediscovered the joy of doing mathematics at the primary and middle school level.