This book supplies the reader with a thorough grounding in number systems, modular arithmetic, combinatorics, networks and graphs, coding theory and recurrence relations. Preface, Introduction: The Fascination of Numbers, Russian Multiplication, Divisibility, Other Types of Numbers, Miscellaneous Problems, Interlude: Proof by Induction, The Sigma Notation for Summation, Miscellaneous Problems, Number Systems, Clocks and Compasses and Computers, Number Bases, Greatest Common Divisor, Modular Arithmetic, Combinatorics, Binomial Coefficients, Pigeonhole Principle, Inclusion and Exclusion, Probability, Codes, Examples of Codes, Hamming Distance, Linear Codes, Decimal Codes, BCH Codes, Cryptology, Recurrence Relations, Iteration, First Order Linear Difference Equations, Second Order Linear Difference Equations with Constant Coefficients, Graphs and Networks, Definitions, Classes of Graphs, Optimization in Networks, Further Reading, Index.