The set of positive integers is the set of all positive integers and integers, excluding 0 from the set of natural numbers until infinity. Positive integer sets usually use symbols N+, N*, N 1, N >；; 0 means.

There are positive numbers and negative numbers in mathematics, which are represented by the number axis. The starting point is zero, the arrow pointing (usually to the right) is positive, and the arrow pointing in the opposite direction (usually to the left) is negative. A set is a structure that includes several objects (it can include 0 objects, that is, an empty set).

The set of positive integers can be represented by symbols N+, N*, N 1, n >; 0 means. Where n stands for natural number set, z stands for integer set,+stands for all elements in number set are positive numbers, * stands for the number set in which element 0 is excluded (for example, R* stands for the number set in which element 0 in R is excluded, that is, R*=R\{0}=R-∪R+=(-∞, 0)∩(0).