1. At first digit we can put any number except
0So, first digit can be filled with 4 ways (2,3,4,5 can only be used)
2. At second digit we can put any number out of remaining numbers (as 1 is used at first digit place)
So, it can be filled with 4 ways
3. At third digit we can put any number out of remaining numbers (as of now 2 digits has been used)
So, it can be filled with 3 ways
4.At fourth digit we can put any number out of remaining numbers (as of now 3 digits has been used)
So, it can be filled with 2 ways
5. Similarly , fifth digit can be filled with 1 way
therefore, Total digits formed =4∗4∗3∗2∗1=96