Set Union

The union of two sets consists of all the elements that are in both sets. Any elements in both the originating sets are single elements in the union set. If the sets are disjointed, where there are no elements in common, then the number of elements in the union can be found by the addition of the total number of elements. The union of more than two sets is the union of two sets taken as a union with the third set and so forth. The associative law and the commutative law for sets states that it does not matter which two sets are taken first or in what order they are taken. The union of two sets is different from the intersection of two sets in that the element has to be in both sets for it to be in the set intersection.

The union of the set of numbers (1, 2, 3, 4) and the set of numbers (3, 4, 5, 6) is the union set (1, 2, 3, 4, 5, 6).

The union of the set of numbers (1, 2, 3, 4) and the set (5, 6, 7, 8) is the union set (1, 2, 3, 4, 5, 6, 7, 8).

The union of the set of numbers (1, 2, 3, 4) and the set (1, 2) is the union set (1, 2, 3, 4).