Let me give you an example: 8 students, choose 5 students to stand in a row. How many different standing positions are there?
First place: 8 students can stand. There are eight situations.
Second place: Because one classmate stood in the first place, there are seven other students who can stand. There are seven situations.
Third place: There are six situations in the competition. ...............
Fourth place: There are five situations in the competition. ...............
Fifth place: There are four situations in the class. ...............
The station method of * * is the product of these five numbers.
8X7X6X5X4
=56X 120
=6720 (species)
Think for yourself! It should be understandable.