The number π is perhaps the most surprising and paradoxical in the world of mathematics. Despite the fact that many books are devoted to it, it is rightfully considered the most studied and it is quite difficult to say anything new about it, it still attracts the inquisitive minds of researchers. For people far from mathematics, the number π is surrounded by many mysteries. Do you know why scientists count the decimal places of pi? Why do we need a list of the first billion digits of π? Is it true that science knows everything about the number π and its signs? This book will help you find the answer to these and many other questions.