Whole (natural) numbers

Natural numbers  –  numbers, which appear as a result of calculus of single subjects: peoples, animals, birds, trees, different wares and so on. Series of natural numbers:  1,  2,  3,  4,  5,  …  is continued endlessly and is called  natural series.

Integers  –  natural numbers and zero:  0,  1,  2,  3,  4,  5, … . Concept "integers" is expanded in the section  "Negative numbers" of the part “Algebra”.