Question

Find the cardinal number for the following sets.

A​ =​ {102​, 103​, 104​, 105​,..., 155​}      
B​ = ​{102​, 104​, 106​, ​..., 252​}

Answer 1

Cardinal number, more commonly called cardinality, is the number of members of a given set.

For example, if P={1,4,6}, cardinality is 3 because there are three member in the set.

For A, the numbers run consecutively from 102 to 155, so there are (155-102)+1=54 members. The cardinality is therefore 54
Similarly, for B={102,...252}, there are (252-102)+1=151 members. So the cardinality is 151.