Preface 3 이 책의 특징 4 TOPIC 1 Beginning with Combinatorics 9 1.1 Multiplication and Addition Principle................. 10 1.2 Principle of Inclusion and Exclusion.................. 12 1.3 Practices.............................................................. 13 TOPIC 2 Continuing with Combinatorics 31 2.1 Case enumeration and Complements................. 32 2.2 Indistinguishables and Distinguishables............ 34 TOPIC 3 Ending with Combinatorics 53 3.1 Probability with restrictions............................... 54 3.2 Combinatorial Probability................................... 56 3.3 Practices ............................................................. 57 TOPIC 4 Beginning with Number Theory 79 4.1 Divisor and Remainders...................................... 80 4.2 Parity and Modular Arithmetic............................ 82 4.3 Practices ............................................................. 83 TOPIC 5 Ending with Number Theory 99 5.1 Divisibility and Modular Arithmetic................... 100 5.2 Chinese Remainder Theorem.............................. 102 5.3 Base Expression and Modular Expression......... 103 5.4 Practices ............................................................. 104 TOPIC 6 Beginning with Geometry 121 6.1 Basic Guidelines for Plane Geometry Problems.122 6.2 Angle Bisector and Perpendicular Bisector........ 123 6.3 Practices ............................................................. 124 TOPIC 7 Ending with Geometry 137 7.1 Quadrilaterals and Cyclic Quadrilaterals............ 138 7.2 Circles ................................................................ 139 7.3 Practices ............................................................. 140