This collection includes the books “Entertaining Arithmetic”, “Entertaining Geometry” and “Entertaining Algebra” by the remarkable popularizer of science Yakov Isidorovich Perelman. We present to your attention excerpts taken from the original author's texts: "Entertaining geometry in the free air and at home" 1933, "Entertaining arithmetic" 1926, "Entertaining algebra", 1937. Our publication does not pretend to be a textbook, but only trying to introduce the children to the world of mathematics. This fascinating book will introduce the reader to the wonderful world of numbers, numbers and geometric shapes. For middle schoolers, students and technical school students, for everyone who wants to fill the gaps in their education.