1.3.5 Cardinality

The cardinality of a set refers to the number of elements present in that set. It helps us understand how many distinct elements are contained in the set. The cardinality of a set  is denoted by () or ||.

To find the cardinality of a set, you simply count the number of distinct elements it contains.

Example 1.17. For instance, the cardinality of set {2, 4, 6, 8} is 4, as it contains four distinct elements.  Similarly, the cardinality of set {, , , , } is 3, as only the unique elements (,  and ) are counted.