Combinatorics

Selecting groups of objects where the arrangement of the objects is not important

Combinations

Selecting objects rather than arranging objects, that is the difference between a combination and a permutation

When solving combinatorics questions, a decision needs to be made about the type in order to choose an appropriate solving strategy

If we don’t care about the way objects are arranged, it becomes a combination

Looking at the situation where the actual arrangement is not important, as well as some other ideas that may save some time