Open main menu Home Random Nearby Log in Settings Give to Wikipedia About Wikipedia Disclaimers Search cardinality of the set of all natural numbers Language Watch Edit version 1.0.2 (change every time you update a partial) Aleph null (also aleph naught or aleph 0 ) is the smallest infinite number . It is the cardinality (size) of the set of natural numbers (there are aleph null natural numbers). Georg Cantor invented and named the concept. The symbol for aleph null is ℵ ℵ 0 {\displaystyle \aleph _{0}} . [1] Aleph-naught, the smallest infinite cardinal number It is the first infinite number in a series of infinite cardinal numbers . In fact, it is the size of any set which can be matched with the natural numbers. [2] The set of algebraic numbers , for example, has cardinality ...