Question

How many numbers of 4 digits can be formed our of the digits 1, 2, 3 ...9 if

repetition of digits (i) not allowed (ii) allowed​

Answer 1

Answer:

8000000

Step-by-step explanation:

1234,5678,90

Answer 2

I.

$4\cdot3\cdot2\cdot1=24$

II.

$4^4=256$