Cardinal Number

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Cardinal Number
  • A whole number that answers the question “How many objects in a set?”
  • Cardinal numbers are a product of set theory.

Supplementary definitions

Wikipedia svg logo-en.svg  Cardinal number
In mathematics, cardinal numbers, or cardinals for short, are generalized numbers used to measure the cardinality (size) of sets. For finite sets, the cardinality is given by a natural number, which is simply the number of elements in the set. There are also transfinite cardinal numbers that describe the sizes of infinite sets.

This extract is licensed under the Creative Commons Attribution-ShareAlike license. It uses material from the article "Cardinal number", retrieved 1 Jan 2009.


The cardinal number of the set [math]A=\left \{2, 4, 9, 7, 1, 8\right\}\,[/math] is [math]6\,[/math].

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Tip: Count the number of items in the set [math]A[/math] above

The cardinal number of the set [math]G=\left \{\alpha, \beta, \gamma, \delta, \epsilon, \zeta, \eta, \theta, \iota, \kappa, \lambda, \mu, \nu, \xi, \mathit{o}, \pi, \rho, \sigma, \tau, \upsilon, \phi, \chi, \psi, \omega \right\}\,[/math] is [math]24\,[/math].