In mathematics, the capital symbol z is used to represent the set of all integers, including positive integers, 0 and negative integers.

The set of all positive integers is called positive integer set, which is denoted as N*, Z+ or n+; The set of all negative integers is called negative integer set, which is denoted as z-; The set of all non-negative integers is called the set of non-negative integers (or natural number set) and is denoted as n.

Integer parity

1, the square of odd number can be expressed as (8m+ 1), and the square of even number can be expressed as 8m or (8m+4).

2. If the product of a finite number of integers is odd, then every integer is odd; If the product of a finite number of integers is even, at least one of these integers is even; The sum and difference of two integers have the same parity; If the square root of an integer is an integer, then both have the same parity.