Yakov Isidorovich Perelman (1882-1942) was neither a physicist, nor a mathematician, nor an astronomer. He graduated from the Forestry Institute in St. Petersburg (now SP6-GLTU). Perelman was also neither a writer nor a teacher, but he corresponded with major scientists and writers from all over the world, worked on compiling new textbooks and problem books in mathematics and physics, gave more than two thousand popular lectures, wrote about a hundred popular science books and countless magazine articles. He did not make any scientific discoveries or inventions, but participated in the development of the project of the first Soviet anti-hail rocket, became the initiator of the country's maternity time, as well as one of the founders of the genre of popular science literature and the author of the term “science fiction.” Yakov Isidorovich did not have academic degrees or titles, but grateful readers in their letters invariably addressed him “Dear Professor!” In his writings, Perelman presented complex scientific problems in his own unique style, doing it with amazing clarity and visualization. In the most seemingly dry and boring topics, he was able to find bright, fascinating features, and they became extremely understandable even to an unprepared reader. It is not surprising that the books of the “People's Professor of the Soviet Union” have gone through dozens of reprints, have been translated into many languages of the world, and their total circulation amounts to tens of millions of copies. This collection includes four works by Perelman - the book “For Young Mathematicians. The first hundred puzzles" and "For young mathematicians. The Second Hundred Puzzles", chapters from the collective collection "Science at Leisure" and a selection of selected questions and problems published by the author in 1906-1940. in various Russian and Soviet magazines. During the editing, some outdated numbers were only replaced and some additions and notes were made. At the same time, whenever possible, the spirit of the time when these articles were created was preserved. At that time, the airplane was usually called an airplane, Albert Einstein was a modest employee of the Patent Office, and the English science fiction writer Herbert Wells delighted readers with his new works. However, the scientific content of Yakov Isidorovich’s articles will never become outdated. Most of the drawings in the collection, excluding publications in magazines, were made by the staff artist of the Leningrad publishing house "Vremya" Yuri (Georgy) Dmitrievich Skaldin (1891-1951), who worked closely with Perelman himself
