Compute the permutation.

how many positive integers of 3 digits each can be formed with the digits 1, 8, 9, 2, 7, 6, 4, and 3, if no digit is repeated in a number?

answers:
27,
336,
512

So you have 8 digits (number available) to form 3 digit numbers (number selected).

Using the formula  where a is the number of available digits, P is the permutation function and c is the number of digits to be selected.

The number of three digit numbers that can be formed = 
                                                                                       = 336

                                                 O R

By using the formula  where a is the number of available digits and c is the number of digits to be selected.

⇒  

⇒  

⇒ Permutation = 336