Question

Find the number of possible choices for a 3-digit PIN (personal identification number) if the digits cannot be repeated.

Answer 1

The number of possible choices for a 3-digit Personal Identification Number (PIN) if the digits cannot be repeated:

$$A_{10}^3={10! \over (10-3)!}=10\cdot9\cdot8=720$$

There are $720$ possible choices for a 3-digit Personal Identification Number (PIN) if the digits cannot be repeated.