1.1 Subgroups of the Integers
1.2 Greatest Common Divisors
1.3 The Euclidean Algorithm
1.4 Prime Numbers
1.5 The Fundamental Theorem of Arithmetic
1.6 The In nitude of Primes
1.7 Congruences
1.8 The Chinese Remainder Theorem
1.9 The Euler Totient Function
1.10 The Theorems of Fermat, Wilson and Euler
1.11 Solutions of Polynomial Congruences
1.12 Primitive Roots
1.13 Quadratic Residues
1.14 Quadratic Reciprocity
1.15 The Jacobi Symbol .