Question

A password consists of four different letters of the alphabet. How many different possible passwords are there?

Answer 1

Well, if they're different, that means that letters cannot be repeated. And keep in mind that there are 26 letters in the alphabet.
If we're finding combinations of letters, what do you think we should start with? :)

Answer 2

a

Answer 3

That might take a while though. What's much faster is to multiply possible combinations. Lets try on a smaller scale - finding a 3-letter password with letters a,b, and c, where the letters are different.
For the first letter of the password, we have 3 possible options. For the second letter, we have only 2 options because we already used one of the 3 for the first letter. That leaves us with 1 option for the third letter.
We take these variables and multiply to find number of combinations. So:
3 x 2 x 1 = 6 possible combinations! If you actually take time to match them up, you also get this.

Answer 4

So, knowing the method, try creating the equation with 26 letters, like in the alphabet.

Answer 5

so there are 6 possible passwords

Answer 6

?

Answer 7

Yes, but that's for if we only have 3 options. If we have 26, we organize the question the same way, so ..
26 x 25 x 24 x 23 = ?
Does that make sense?

Answer 8

358800

Answer 9

Yes, that's the answer.
Ask if you need more clarification - it's the same principle as the smaller example I gave, though :)

Answer 10

.