"Your free time. Entertaining tasks, experiments, games" - this is an unprecedentedly entertaining book, incorporating all the best published over the past 30 years in the puzzle genre. 3 eminent authors Kolotova B.I., Logovsky I.K., Bolkhovitinov V.N., who have well-deserved awards and scientific degrees in various fields of science. Many puzzles and tasks from the collection were published in different domestic and foreign collections and magazines at different periods of time, but never when they were presented in the same book!