Question

How many $3$ -digit number can be formed from the digit $1,2,3,4$ and $5$ assuming that
(i) repetition of the digit is allowed?
(ii) repetition of the digits is not allowed?

Answer 1

(i) for repition is allowed

By fundamental principle of counting , we have

$5^3$ 3-digit no. which can be formed from no.s 1,2,3,4,5

i.e.125 (ans.)

(ii) for repition not allowed

we have ,$5\times 4\times 3i.e.60$

3-digit no.s which can be formed from 1,2,3,4,5

so 60(ans.)