Like other introductions to number theory, this one includes the usual curtsy to divisibility theory, the bow to congruence, and the little chat with quadratic reciprocity. It also includes proofs of results such as Lagrange's Four Square Theorem, the theorem behind Lucas's test for perfect numbers, the theorem that a regular n -gon is constructible just in case phi( n ) is a power of 2, the fact that the circle cannot be squared, Dirichlet's theorem...