You have a total of $9$ people to choose from. Of these $9$ people you are supposed to create a group of $4$. How many different ways can the new group look?
This is my reasoning:
To the new group, the first person can be chosen in $9$ ways, the second in $8$ ways, the third in $7$ ways and the fourth in $6$. Thus there can be $9 * 8 * 7 * 6 = 3024$ different types of groups with $4$ people.