# Math Help - Number of 4 digit codes in logarithmic form.

1. ## Number of 4 digit codes in logarithmic form.

A security PIN code is four digits long. Each digit could have the value 0 to 9. If an office building needs 10 security PINs, express the number of codes in logarithmic form with base 10.

2. ## Re: Help needed!

Originally Posted by BlazingJatt
A security PIN code is four digits long. Each digit could have the value 0 to 9. If an office building needs 10 security PINs, express the number of codes in logarithmic form with base 10.
If digits can be repeated as in $9009$ then there $10^4$ different codes.

If digits can not be repeated as in $1079$ then there $10\cdot 9\cdot 8\cdot 7$ different codes.

In either case choose ten of that number.