Question

How do you find the number of permutations of the first 13 letter of the alphabet taking 4 letters at a time?

Answer 1

Answer:

17160 ways

Step-by-step explanation:

Given a total of n objects taken r at a time the the permutation formula is given by :

P(n, r) = n! /(n - r)!

In our case we have that :

n = 13

r = 4

P(13,4) = 13!/(13 - 4)!

= 13!/9!

= (13 × 12 × 11 × 10 × 9!)/ 9!

= canceling out 9! We have :

= 13 × 12 × 11 × 10 = 17160

This is the permutations of 13 alphabets taken r at a time.

Therefore there are 17160 ways of picking n, objects r at a time.