Cartesian product

The cartesian product is like a multiplication table. The cartesian product of two sets of numbers (A and B) shows all the possible combinations of numbers you can get when you combine one number from A with one number from B. For example, if A is the set {1,2} and B is the set {3,4}, then the cartesian product of A and B would be the 4 combinations {1,3}, {1,4}, {2,3}, and {2,4}.