from a pool of 12 candidates in how many ways can we select president, vice-president, secretary and a treasurer if each of the 12 candidates can hold any office?

In how many ways can we select two vertices in a hexagon?

A class consists of 40 girls and 60 boys. In how many ways can a president, vice president, treasurer and secretary be chosen i th treasurer must be a girl, the secretary must be a boy and a student may not hold more than one office?

In how many ways 2 persons can be selected from 4 persons?

How many ways 3 students can be selected from 50 students ?

There are 6 candidates for 3 posts. In how many ways can the posts be filled?

In how many ways can 12 books be divided in 3 students equally?