Question

How many 4-digit personal identification numbers are possible if the number cannot contain a zero? a. 5,040 b. 6,561 c. 9,000 d. 10,000 please select the best answer from the choices provided a b c d

Answer 1

b. 6,561

Explanation:

You want to know the number of 4-digit numbers that do not contain 0.

Permutations

Each of the digits may have any of 9 values. The number of possibilities is the product of the number of possibilities for each of the digits:

9×9×9×9 = 6561

The number of possible 4-digit PINs is 6561 if none of the digits is 0.