Question

A security code consists of 9 digits (0–9), and a digit may not be used more than once. How many possible security codes are there?

Answer 1

Answer: 362880 (?)

Explanation:

I believe this question is asking for a permutation, in which I plugged it into my graphing calculator as nPr(9,9) and got that answer.

Answer 2

a

Explanation: