Combinations

Selecting a group of objects when the order does not matter.

A combination is a selection of objects where order does not matter.

$$^nC_r = \frac{n!}{r!(n-r)!}$$

Note: Choosing a team of 3 from 5 people is a combination problem; arranging 3 people in a line is a permutation problem.

Lesson 12 of 27