Question

Find the number of 4 digit numbers that can be formed using the digits 1,2,3,4,5 if no digits is no repeated

How many of these will be even?

Answer 1

5 different numbers, 2 even

Explanation:

Since we have 5 digits and they are non repeating we can use the permutation formula:

`P(n, k) = (n!)/(k!), $where $ k \leq n ; k, n \in \mathbb{N}`

It gives us the amount of ways to arrange k objects out of n objects without repetition, but order does matter.

In our case the amount of 4 digit numbers that can be formed using the digits from 1 to 5 is:
`P(5, 4) = (5!)/(4!) = 5.`

And out of those 5, only 2 are even