Cardinal numbers are counting numbers 1,2,3,4, etc
If I wanted the set of cardinal numbers between 8.6 and 15.19 then the answer would be
{9, 10, 11, 12, 13, 14, 15}
So that is an example of a cardinal set.
However
The cardinal number OF the above set is 7 because there are seven elements in the set.
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I would like another mathematician to comment on this answer. I have done very little work with set notation etc.