Find all 3 digit numbers formed with the digits 1,2,3,4 and 5 if
(i) repetition of digits is allowed?
(ii) repetition of digits is not allowed?

Explanation

(i) When repetition of digits is allowed:
No. of ways of selecting 1st digit = 5
No. of ways of selecting 2nd digit = 5
No. of ways of selecting 3rd digit = 5
`:.` Total no of ways `= 5 xx 5 xx 5 = 125`
(ii) When repetition of digits is not allowed.
No. of ways of selecting 1st digit = 5
No. of ways of selecting 2nd digit = 4 No. of ways of selecting 3rd digit = 3
`:.` Total number of ways `= 5 xx 4 xx 3 = 60`