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

The attempt at a solution

y=4log(x-10)

I don't know how to do the question, but my best attempt produced what you see above.

4 represents the # of digits.

x-10 because of the range 0-9.