# Cardinal number of a set explained with examples

Learn and know what is the meaning of cardinal number of a set? And how to find it. In set theory, cardinal number of a set topic is very easiest and simple to understand. Do you know what is the method or process to find cardinal number of a set? For this we need to list all the elements of a given set. If the set is in set builder form or descriptive form then write it in list form. If it is in roster form then no problem. Now coming to our main point. How to calculate cardinal number of a set, it is very easy just count all the elements in the set. You will get the cardinal number of that set. See the below and learn definition of cardinal number of a set.

## The definition of a Cardinal number of a set as follows:

The Number of elements present or contains in any given set is called as cardinal number of a set. If the given set is D then Cardinal number of a set is represented by n(D). Do you know, equivalent sets are described or defined by the cardinal number only.

Note:

If the given set F is finite then n(F) is finite and if the given set L is infinite then n(L) is infinite.

Cardinal number of a set for a Null set is 0 because it doesn’t contain any elements.

For a singleton set, the cardinal number is 1 because it contains only a single element.

Examples:

B = {1, 8, 9, 14, 5, 7, 36, 47, 12}

n(B) = 9

K = multiples of 9 less than 50

n(K) = 5

P is a set of composite numbers between 10 to 20. Now we can’t write directly the cardinal number. So first list out all the elements of set P. P = {12, 14, 15, 16, 18}. Therefore n(P)= 5. 