Question

given the digits 0-9 how many three digit arrangements are there in a lock if no number can be used twice?

Answer 1

720 Arrangements

Explanation:

Given the numbers could be from 0 - 9 and none of them is to be repeated.

The first place could be filled in 10 ways. (0 - 9)

The second place could be filled in 9 ways. (Excluding the one in the first place).

The third place could be filled in 8 ways. (Excluding the two numbers in the first two places).

Therefore, the total number of arrangements possible for the lock is:
`$ 10 * 9 * 8 $` = 720 ways.