Question

A number lock has five digits (0-9). In the code, numbers cannot be repeated. How many different codes are available?

Answer 1

Explanation:

The first digit can be any of 10 choices.

The second can be any of 9 choices (since no repetition).

The third digit can be any of 8 choices.

The fourth digit can be any of 7 choices.

The fifth digit can be any of 6 choices.

`\text{Possible codes}=10*9*8*7*6=30240`