This book, together with the previously published books "Tasks on Planimetry" 1 and "Tasks on Algebra, Arithmetic and Analysis" is a single collection of problems in mathematics for students of physico-mathematical classes. It presents almost all the topics in mathematics that are studied in school in specialized classes. The basis of this collection of problems are problems from the journal "Quantum", problems at different times offered at mathematical Olympiads, and problems from the archives of mathematical Olympiads and mathematical circles. The book includes about 800 problems in stereometry, provided with detailed solutions. Most of the tasks are related to the school curriculum .. Their difficulty level is mostly somewhat higher than normal school tasks, and there are also some very difficult tasks designed for students in math classes. Tasks are broken down into cycles related to the overall idea of the solution. Within each cycle, problems are arranged in order of increasing difficulty. For schoolchildren, teachers of mathematics, heads of mathematical circles, students of pedagogical institutes and universities .