In this book we will talk about ethnomathematics, that is, about the features of calculation methods inherent in different peoples.  Although the history of modern mathematics is part of the European cultural heritage, it is based on non-academic strata that existed long before the emergence of modern culture.  Ethnomathematics covers the entire list of mathematical tools created by different peoples to solve certain problems.  Of course, it is far from the academic science we are familiar with and, rather, relies on practical experience, and therefore is doubly interesting.  This book is a way to take a mathematical journey around the world and learn a lot about the cultures of different peoples.