Question

In how many ways a five letter word can be formed with 8 letters

Answer 1

5*5*5*5*5*5*5*5 = 5*10^8

Answer 2

If repetition is allowed then no of ways =8×8×8×8×8=32,768 ways.
else if repetition is not allowed then no of ways =8×7×6×5×4=6,720 ways.