However, one has to agree that in recent years the interest in number theory is also increasing due to its applications in areas like error-correcting codes and cryptography. Keeping this in mind, we or- ganized these conferences to bring together mathematicians taking up research in number theory for either or both of the above reasons and this volume contains papers in various areas of number theory, such as combinatorial, algebraic, analytic and transcendental aspects, arith- metic algebraic geometry, as well as graph theory and cryptography. While some papers do contain new results, several of them are expos- itory articles on some interesting themes mentioning open quest ions , which will be useful to young researchers.