Doppelschlaghauptstadt 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.

Das Symbol „Doppelschlaghauptstadt Z“ ist im „Buchstabenartige Symbole“ Subblock des „Buchstabenähnliche Symbole“ blocks enthalten und wurde als Teil der Unicode-Version 1.1 im Jahr 1993 genehmigt.