Before you is a well-known book by Emelyan Ignatievich Ignatiev (1869-1923), a teacher and generally recognized classic of popular mathematical literature. "In the Realm of Ingenuity" has been reprinted many times and has consistently been successful: the tasks, puzzles and riddles from this book have been well known to all fans of intellectual warm-up for over a hundred years. The entertaining tasks presented in the book have varying degrees of difficulty. To solve them, an advanced knowledge of mathematics is not required, a basic level of knowledge of arithmetic and geometry and ingenuity is enough. Clearly stated solutions and answers are located at the end of the book.