Entertaining arithmetic. Perelman Ya. I.

Why do people like "round" numbers? How is the expression “staying on beans” associated with arithmetic? How to read the thoughts of your friends with matches? What distance is the ray of light overcomes for a millionth fraction of a second? This is only a small part of the curious arithmetic questions, the answers to which you will find in “entertaining arithmetic”. This book is a fascinating excursion into the history of what ways people of different eras, cultures and countries considered it and how it was reflected in our reality. At the same time, this is an affordable manual with which you will learn how to add, subtract, multiply and share quickly and without errors. The intricacies of the account and cunning arithmetic tasks in “Entertaining arithmetic” are accompanied by detailed comments and explanatory illustrations.