The symbol ∪ is called the union. You find the union between two sets by adding all the members in each of the sets. If both of the sets have the same member, only add it once. As sets can't have duplicate members.
A ∪ B = {1,2,3,4,6}
The intersection between two sets is all the members that belong in both A and B.
A ∩ B = {2}
