From Conservapedia - Reading time: 1 min
In mathematics, a cardinal number is a set that represents a generalization of the number of elements of the set.
In set theory, the usual counting numbers are represented by sets.
For example, 10 is a set. There are many ways to represent 10 as a set, but the most widespread [1] takes 10 = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 }.