Question

The number of numbers consisting of four different digits that can be formed with the digits 0, 1, 2, 3 is :

• A. 18
• B. 24
• C. 30
• D. 72

Answer 1

Answer: (A)

18

Answer 2

The number of numbers consisting of four different digits that can be formed with digits 0, 1, 2, 3 = 4! - 3! = 4. 3! - 3! = 3!(4 - 1) = 3! . 3 $\Rightarrow$ 3.2.1.3 $\, \Rightarrow$ 18