डबल-स्ट्रक कैपिटल एन ℕ

The set of natural numbers ℕ = {1, 2, 3, ...} consists of numbers used in counting. Sometimes, 0 is added to this set. Sets that have the same cardinality as ℕ (countable sets) are the ‘smallest’ of infinite sets.

Sets ℕ , ℤ , ℚ , ℝ , and ℂ are often written in bold (for example, in the works of Nicolas Bourbaki), and on blackboards and manuscripts, they are written in double letters. American mathematicians introduced double font in printed texts, and it became popular with the famous 1965 textbook on complex analysis by Gunning and Rossi.

संकेत ‘डबल-स्ट्रक कैपिटल एन’ ‘अक्षर चिह्न’ उपखंड में शामिल है, जो ‘पत्र-जैसे प्रतीक’ खंड का हिस्सा है, और यह Unicode संस्करण 1.1 के भाग के रूप में 1993 में स्वीकृत हुआ था।