The first part of the book, dedicated to the number e, begins with the neper and ends with Musta's inequality. Elementary functions are part of the general culture of any mathematics user. We warmly refer to our monograph dealing with this delicate subject of mathematics.
The second part of the book starts with monotone strings and ends with Riemann's zeta function. In this part we have presented various and varied problems related to the study of the convergence of some remarkable real strings.