Question

How many different four-letter passwords can be formed from the letten A B, C, D, L, E. G. H and if no repetition of letters is allowed?

Answer 1

1680

Explanation:

There are 8 options for the first letter.

There's no repetition, so there are 7 options for the second letter.

Similarly, there are 6 options for the third letter and 5 options for the fourth letter.

The number of permutations is:

8 × 7 × 6 × 5 = 1680