Suppose you find six articles related to the topic of your research paper. In how many ways can you choose four articles to read? 30 15 720 360

This is a case of choosing objects from a set, where order matters.

The number of ways you can choose some objects from a set when order matters is called variations.

The formula of variations is:

Vm, n = m! / (m - n) !

In this case it is the selection of four articles from a set of six articles = >

V6,4 = 6! / (6-4) ! = 6*5*4! / 4! = 6*5 = 30

Answer: 30