In mathematics, the letter Z represents an integer set, and the set composed of all integers is called an integer set. Integer sets include all positive integers, all negative integers and zeros, and integer sets are usually represented by z in mathematics.

The reason why Z stands for integer set is because it involves the contribution of a German female mathematician named Nott to ring theory.

In 1920, she introduced the concepts of "left module" and "right module". The ideal theory of the whole ring written in 192 1 is a milestone in the development of commutative algebra. Because she is German, the integer in German is called Zahlen, so she recorded the integer ring as Z at that time, and the integer set has been represented by Z since then.

Several commonly used symbols in mathematics can be used directly without explanation: n stands for natural number set, z stands for integer set, q stands for rational number set, r stands for real number set, and c stands for complex number set.

N stands for the set of natural numbers in the set. A non-negative integer set is a specific set, which refers to the set of all natural numbers, and is commonly represented by the symbol n. Non-negative integers include positive integers and zeros.