Book «School Olympiads of SPbU 2021 . Mathematics”, created by a team of authors, is a unique and rich resource for those who seek to test their knowledge and prepare for participation in prestigious school competitions in mathematics . This edition is not just a collection of problems, but a real guide to the world of intellectual challenges, revealing the secrets of successful solving of complex problems and demonstrating the wealth of mathematical thinking. The focus of this book is a variety of problems covering a wide range of topics, from classical algebra and geometry to elements of number theory and combinatorics. The authors, experienced teachers and winners of the Olympiad, carefully selected tasks that not only test the basic knowledge, but also stimulate the development of logical thinking, creativity and analytical abilities. Each task is accompanied by an analysis that allows you to understand not only the right solution, but also the approach to finding it, which makes the book a valuable tool for self-study and preparation for competitions. «School Olympiads of St. Petersburg State University 2021 . Mathematics is designed for high school students, ambitious students who want not only to prepare for the Olympics, but also to expand their horizons in the field of mathematics. This book will be useful both for those who already participate in the Olympiads and want to improve their level, and for those who are just starting their way in the mathematical competition. It is suitable for students of grades 9-11, as well as for teachers and parents looking for effective teaching materials to support young talents. The peculiarity of this publication is not only the wealth of tasks, but also a special style of presentation of the material. The authors use clear and accessible language, making complex topics understandable and interesting. The book contains many illustrations and diagrams that help to visualize complex ideas, as well as tips and hints that contribute to the development of independent thinking. As a result, the reader does not just solve problems, but learns to see mathematics as an exciting game that reveals the secrets of the surrounding world. Book «School Olympiads of SPbU 2021 . Mathematics is not only a practical tool, but also a source of inspiration for those who dream of reaching new heights in mathematics. It is worthy of attention of those who appreciate intellectual challenges, likes to solve puzzles and wants to prepare for participation in the Olympiads at the level of St. Petersburg State University. This edition will be a reliable companion on the way to the Olympic victories and the expansion of mathematical horizons. If you are looking for a book that will help you not only prepare for the Olympics, but also open new horizons in mathematics, "School Olympiads SPbU 2021. Mathematics” is exactly what you need. It can be compared with mathematics textbooks for the Olympics, collections of tasks for high school students and books on preparation for intellectual competitions. Get inspired, decide and reach new heights with this unique edition!