Double-Struck Capital 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.

Symbol „Double-Struck Capital Z” jest zawarty w podbloku „Symbole podobne do liter” bloku „Letterlike Symbole” i został zatwierdzony jako część wersji Unicode 1.1 w 1993 roku.