Let
[math]X := \href{/cs2800/wiki/index.php/Set_comprehension}{\{2n} \href{/cs2800/wiki/index.php/%5Cmid}{\mid} n \href{/cs2800/wiki/index.php/%E2%88%88}{∈} \href{/cs2800/wiki/index.php/%E2%84%95}{ℕ}\}
[/math] be the set of
even natural numbers. Then
[math]│X│ \href{/cs2800/wiki/index.php/Equality_(cardinality)}{=} │ℕ│
[/math].
