The book "Fundamentals of the theory of divisibility of numbers . Solution of equations in integers" by Bardushkina V. In. and his co-authors is a fascinating and deep dive into the world of numbers, which will be a real discovery for all who are interested in mathematics, especially number theory. This work not only illuminates the basic principles of divisibility, but also offers the reader a unique view of the solution of equations in integers, which makes it an indispensable tool for students, teachers and all lovers of mathematics. The book examines the fundamental aspects of the theory of divisibility, starting with simple concepts and ending with more complex concepts. The authors masterfully explain how numbers interact with each other, and how these interactions can be used to solve various mathematical problems. Each chapter is imbued with clear examples and practical tasks, which allows the reader not only to assimilate the theoretical material, but also to apply it in practice. This makes the book particularly useful for students preparing for exams or wanting to deepen their knowledge of mathematics. Who can like this book? First of all, it will be interesting for students and schoolchildren studying mathematics at a deeper level . It will also be appreciated by teachers who are looking for high-quality materials for the preparation of lessons or seminars .. Lovers of puzzles and mathematical problems will find in it a lot of interesting and fascinating exercises that will help develop logical thinking and analytical abilities. The book is suitable for readers aged 15 years and older, as it requires a certain basic training in mathematics. The topics raised in the book go beyond just studying numbers. The authors address issues related to algorithms, number theory and even some aspects of cryptography, which makes the material relevant in today's world, where mathematics plays a key role in information technology. The book also emphasizes the importance of numbers in everyday life and in various scientific fields, which makes it particularly valuable for those who want to understand how mathematics affects our world. The style of Bardushkin and his co-authors is distinguished by clarity and accessibility. They are able to explain complex things in simple language, which makes the book understandable even for those who are not professional mathematicians. This quality is especially important when it comes to abstract concepts such as divisibility and equations. In their works, there is a desire to convey to the reader not only knowledge, but also a love for mathematics, which makes reading a book a real pleasure. If you are interested in works such as Gauss's Theory of Numbers or