This book is actually a collection that includes the three best books by Jacob Perelman on mathematics. These are "Entertaining Arithmetic," which was first published in Leningrad in 1926, "Entertaining Algebra" in 1937, and "Entertaining Geometry" in 1933. All three books have enjoyed and still enjoy well-deserved attention. Many generations of people in our country meet these books with great interest, rereading them and letting them read to their children and grandchildren.