Whiles I haven't completed this book yet because I have 2 others that I've been comparing. This one is certainly the most outstanding and interesting. I believe if one stays with this book and do the exercises provided there will be hardly any mental math problems you can't solve. I'm talking addition subtraction multipling and division.The book is well written and narrated so you can easily understand whats being presented;all you have to do is follow the  instructions and do the exercises. Again a great book to help you improve or master your math efficiency!<br><br>
  
Secrets of Mental Math: The Mathemagician's Guide to Lightning Calculation and Amazing Math Tricks