Preface 3 이 책의 특징 4 TOPIC 1 Divisor and Remainders 9 1.1 Divisor and Remainders 10 1.2 Parity and More 13 1.3 Prime Factorization 23 TOPIC 2 Least Common Multiple and Greatest Common Divisor 35 2.1 Least Common Multiple 36 2.2 Greatest Common Divisor 46 2.3 Eulidean Algorithm and Bezout's Identity 56 2.4 Application of LCM and GCD 68 TOPIC 3 Counting Divisors and More Arithmetic 79 3.1 Counting Divisors and More Arithmetic 80 TOPIC 4 Base-N Expression 97 4.1 Base-N Expression 98 TOPIC 5 Modular Arithmetic 115 5.1 Basic Knowledge of Modular Arithmetic 116 5.2 Application of Modular Arithmetic 126 TOPIC 6 Mixed Practice 139