Question

A lock requires a 3 number combination using the numbers 0 through 9, none of which may be repeated. How many outcomes are possible?

48

720

12010

Answer 1

720

Explanation:

The lock requires that repetition is not allowed.

The possibles numbers are 0 - 9, that is, 10 digits.

The first number in the combination can be picked from the 10 digits.

This means that there are 10 possible choices.

The second number in the combination can now only be picked from 9 digits.

This means that there are 9 possible choices.

The third number in the combination can now only be picked from 8 digits.

This means that there are 8 possible choices.

Therefore, the number of possible outcomes in the combination is:

10 * 9 * 8 = 720 outcomes