The collection includes 550 problems and puzzles with answers and solutions collected by the famous popularizer of science Yakov Isidorovich Perelman (1882-1942). They were published in books "For young mathematicians. The first hundred puzzles" and "For young mathematicians. The second hundred puzzles," in the collective collection "Science at Leisure," as well as in various Russian and Soviet magazines from 1906 to 1940. The texts are given in the author's edition and in modern spelling. Most of the drawings were made by the staff artist of the Leningrad publishing house Vremya Yuri (Georgy) Dmitrievich Skaldin (1891-1951).