https://tcs.nju.edu.cn/wiki/api.php?action=feedcontributions&feedformat=atom&user=152.26.26.50 2026-05-01T09:48:03Z User contributions MediaWiki 1.45.3 https://tcs.nju.edu.cn/wiki/index.php?title=Cardinal_number&diff=7461 2014-10-08T17:56:51Z

<p>152.26.26.50: </p> <hr /> <div>'''Cardinal numbers''' (or '''cardinals''') are [[number]]s that say ''how many'' of something there are, for example: one, two, three, four, five, six. They are sometimes called '''counting numbers'''.<br /> <br /> The '''[[Set#Cardinality_of_a_set|cardinality]]''' of a [[set]] is the cardinal number that tells how many things are in the set.<br /> <br /> In [[mathematics]], people also study [[infinite]] cardinal numbers. The first infinite cardinal number was named &lt;math&gt;\aleph_0&lt;/math&gt; (pronounced [[Hebrew language#Alphabet|Aleph]]-zero or Aleph-naught) by [[Georg Cantor]]. &lt;math&gt;\aleph_0&lt;/math&gt; is the amount of numbers that are in the group 0, 1, 2, 3, ... keep going forever. Cantor [[Mathematical proof|proved]] that there are many different infinite cardinal numbers that are bigger than &lt;math&gt;\aleph_0&lt;/math&gt;. A famous theorem of Cantor is that the cardinality of the [[real number]]s is larger than the cardinality of the [[natural number]]s.<br /> <br /> ==Other pages==<br /> *[[Ordinal number]]<br /> {{Math-stub}}<br /> [[Category:Number theory]]<br /> [[Category:Cardinal numbers| ]]<br /> <br /> [[ru:Кардинальное число]]</div>

152.26.26.50