The cardinality of any infinite ordinal number is an aleph number. Every aleph is the cardinality of some ordinal. Indeed, infinite sets are characterized as sets that have proper subsets of the same cardinality. Each ordinal associates with one cardinal, its cardinality. The set of computable numbers has the same cardinality as the natural numbers. Similarly, any surjection between two finite sets of the same cardinality is also an injection. They also allow class enumeration, cardinality, disjointness, and equivalence. We note that, per Cantor's proof of the cardinality of Euclidean space, formula 77. Cantor developed important concepts in topology and their relation to cardinality. The number is the set's cardinality, denoted as ||. The algorithm has a total cost linear in the edges cardinality. Cantor proved that the cardinality of the second number class is the first uncountable cardinality. Now we show the cardinality of an infinite interval. The smallest infinite cardinality is that of the natural numbers (formula 14). An example of an instance for the cardinality estimation problem is the stream&colon; formula 10.