sir, what is the meaning of cardinality of a set.how cardinality of a null set 0,please explain.

Cardinality of a set is equal to the number of elements inside the set.

To find the cardinality, count the number of elements in the set , that will give you the cardinality.

For example, A={4,5,6,7,8} has cardinality 5

B={4} has cardinality 1.

 

For a null set, it has no element in it, so number of elements in it is 0 means that its cardinality is also zero.