Check my answer.. if i'm not correct please explain

Question

Solve the following permutation. 5P2
Question 7 options:

1) 240

2) 120

3) 20

4) 5

 

Is it 2) 120?

Answer 1

The right answer is 20.

 

The formula for nPm is n! / (n-m)!

 

So here we have 5x4x3x2 / 3x2. Cancel out the 3x2 on top and bottom and we have 5x4 = 20.

 

Another way to think of it is that we're picking 2 things from 5 things. We have 5 options for the first thing and 4 options remaining for the second thing. 5x4 = 20