A computer system requires users to have an access code that consists of a three-digit number that is not allowed to start with zero and cannot repeat digits. How many such codes are possible?
A) 990
B) 648
C) 729
D) 720

Question

Quizplus · Accepted Answer

There are 9 choices for the first digit (1-9), 9 choices for the second digit (since it cannot be the same as the first), and 8 choices for the third digit (since it cannot be the same as the first two). The total number of possible codes is 9 x 9 x 8 = 648.

A Computer System Requires Users to Have an Access Code