ABSTRACT
Number theory is the study of the integers: . . . ,−3,−2,−1, 0, 1, 2, 3, . . .. Number theorists investigate how the integers behave under addition and multiplication. Often they deal with just the nonnegative integers, 0, 1, 2, 3, . . ., or with the positive integers 1, 2, 3, 4, . . ..
