The set {0, 1, 2, 3) is given. The only operation on the group isaddition.

ff the result of the addition operation is one items of the set, it called internal result,

else it called external result.

The internal result is 4

The external result is 6.

How I represent it by representation of combinatorics:

(1) The number of internal result?

(2) The number of external result?

(3) The number of result that are derive by commutative law?