How many different ways can 8 letters be grouped with no letter being repeated?

Do you mean from the whole pool of 26 letters, how many groups are there with no repeated letters?

Well, if you take one letter, there are 26 choices
Then for the second letter you have a choice of every letter except the one you chose first, so you have 25 choices.
So for each of your first 26 choices, you have 25 choices of second letter, to give you 25x26 total combinations

So for n letter combination, you have 26x25x24... x(26-n) combinations.

Hope this helps :)

That would be 26*24*23*22*21*20*19*18 if I am not mistaken. First you choose any letter, giving you 26 possible choices. Then, you choose any letter besides the one you picked (25 choices) and so on. When you say no letter repeated, I assumed you meant no letter is used twice through-out the whole combination. I also assumed you use all 26 letters. If you didn't, then the answer would be different obviously.

If it's any 8 letters, then the answer is 26(25)(24)... (19) as the other two responses have indicated. If it is 8 specific letters then it is 8(7)(6)(5)(4)(3)(2)(1) or 8! And = 40,320