I'm self-studying number theory and am looking for a standard undergraduate introduction to congruence.
Hardy and Wright has it in pieces that can be uncovered. Gauss, of course, in Disquisitiones Arithmeticae has the presentation in the history of mathematics. Ogilvy's Excursions in Number Theory has a nice intuitive presentation. I like the newer text by Watkins ...
But what I seek is a step-by-step introduction to the theory of congruences that is not leading anywhere in particular except that it would be a solid foundation to move on.
Anybody have a good set of lecture notes out there?
My plan starts with equivalence relations, partitions, etc. and then moves on to congruence.
This may be asking for too many personal opinions but, in a phrase:
what, in your opinion, is a good source for an introduction to congruence?