双线大写 Z ℤ

The set of integers ℤ = {…, -2, -1, 0, 1, 2, ...} consists of the natural numbers (positive integers), their negative counterparts, and zero. The term 「integer」 comes from the German word 「Zahl,」 meaning 「number.」 The set ℤ is countable (equivalent in cardinality to the set of natural numbers ℕ).

The sets ℕ , ℤ , ℚ , ℝ , ℂ are often written in bold font (for example, in the works of Nicolas Bourbaki) or as double-struck letters on blackboards and manuscripts. American mathematicians introduced the usage of double-struck font in printed texts, and it became popularized with the famous textbook on complex analysis by Gunning and Rossi, published in 1965.

符号 「双线大写 Z」 包含在 「字母式符号」 块的 「字母符號」 子块中，并在1993年作为Unicode版本1.1的一部分获得批准。