How many numbers of four digit can be formed with the digits 0, 1, 2, 3 (repetition of digits is not allowed)?

How many numbers of four digit can be formed with the digits 0, 1, 2, 3 (repetition of digits is not allowed)?

A 18

B 24

C 64

D 192

E 256

Solution

Correct Answer: Option A

First digit can be 1, 2, 3 only. (four digit number)

Hence, 3 × 3 × 2 × 1 = 18 ways (with no digit repetition)