Question 681934
4 letter password using letters from A,B,C,D,E,F

By assuming that the first letter is "A",  and the last letter is “F",



Therefore, one has to find two more letters from the remaining 4 letters.

Of the 4 letters, there are 1 B, 1 C, 1 D, and 1 E .

The second and third positions can  have two different letters.

When the two letters are different. One has to choose two different letters from the 4 available different choices. This can be done in 4 * 3=12 ways.


Total number of possibilities  is 12.

1. A,B,C,F

2. A,C,B,F

3. A,B,D,F

4. A,D,B,F

5. A,C,D,F

6. A,D,C,F

7. A,C,E,F

8. A,E,C,F

9. A,D,E,F

10. A,E,D,F

11. A,B,E,F

12. A,E,B,F