The book is released on the occasion of the popular International Mathematics Competition "Kangaroo". This competition takes place every year, during the second fortnight of March. Over 5 million students from 3rd grade of primary school to 3rd grade of high school participate worldwide. The philosophy of the competition is based on the principle that mathematics cultivates thinking and brings intellectual satisfaction, so it should not only be addressed to a few. The questions asked in the competition do not require special mathematical knowledge to solve them. Most can be solved with just common logic. The main characteristic of the topics is simplicity, originality, and the accompanying element of fun.

Although the book is aimed at students, any reader, regardless of age or specialty, can find interesting articles and problems.

The book contains:
- the questions and solutions of the Kangaroo Competition, year 2009, for all levels, a total of 144 questions.
- articles - exercises - problems, from 3rd grade of primary school to 3rd grade of high school. The texts contain exercises that are more attractive and unusual than those in school books.
- entertaining mathematics (numbers with peculiar properties and more).