This book presents topics from mathematics which are relevant and useful to computer science. This book treats basic topics such as number theory, set theory, functions etc. in a simple way. Each chapter has been planned as independent unit so that various interrelated topics can also be read independently. Ample amount of examples and problems are given at the end of each chapter to help both the students and researchers. Hints and answers are also given for the problems in the exercise to help the students for self-learning.