Question

How many 4 digit numbers can be formed using the digits 1, 2, 3, 4 and 5 assuming

that

(i) Repetition of the digits is allowed. (2)

(ii) Repetition of the digits is not allowed. ​

Answer 1

1. 1234,2345 3451,4512,5123,1111,2222,3333,4444,5555,1122,2233,3344,4455,5511
2. 1234,2345 3451,4512,5123,1432,1342,2435,2543,1534,2143,3245,3514,3124,