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Cardinal Number of the Real Numbers
publish date: 2026/05/23 21:45:35.526834 UTC
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What symbol denotes the cardinality of the set of all real numbers \(\mathbb{R}\)?
Correct Answer
\(c\)
Explanation
The cardinal number of \(\mathbb{R}\) is denoted \(c\) (the cardinality of the continuum). It can be shown that \(c = 2^{\aleph_0}\) — the cardinality of the power set of \(\mathbb{N}\). The cardinal \(c\) also equals the cardinality of any open interval or any subset of \(\mathbb{R}\) that contains an open interval. And \(\aleph_0 < c\).
Reference
Introduction to Differential Calculus (Systematic Studies with Engineering Applications for Beginners) - 2012