There are 720 ways of codes are possible.
Explanation:
Given that the code consists of 3 digits, none of which is repeated.
We need to determine the codes that are possible.
The possible ways of codes can be determined using the permutation formula,
where n is the number of choices and r is the number chosen.
Hence, substituting and , we have,
Simplifying, we get,
Cancelling the common terms, we get,
Multiplying, we get,
Thus, there are 720 ways of codes are possible.