Elementary and General Number Theory

Branches that study the integers and their basic properties using the methods that are closest to arithmetic. An entry belongs here when its cited source describes divisibility, primes, congruences and the arithmetic of whole numbers, or the general survey of number theory itself. It does not belong here when the branch relies on heavy tools from algebra or from analysis, which are grouped as algebraic and analytic number theory. The group is the oldest layer of the subject and is where a beginner first meets it.