Pinellas County is a county located in the state of Florida. As of the 2010 census, the population was 916,542. Its county seat is Clearwater, and its largest city is St. Petersburg. Pinellas County is included in the TampaâSt. PetersburgâClearwater, Florida Metropolitan Statistical Area.
Nowadays, we can say in plain English: A set is a well defined collection of objects. The elements or members of a set can be anything: numbers, characters, words, names, letters of the alphabet, even other sets, and so on.
Not to be confused with (recursively) enumerable sets. In mathematics, a countable set is a set with the same cardinality (number of elements) as some subset of the set of natural numbers. A countable set is either a finite set or a countably infinite set. Whether finite or infinite, the elements of a countable set can always be counted one at a time and, although the counting may never finish, every element of the set is associated with a natural number.