A five letter code is to be made by choosing 5 letters from the first 8 letters

Question

A five letter code is to be made by choosing 5 letters from the first 8 letters of our alphabet (a, b, c, d, e, f, g, h).. If repeats are allowed (the same letter may be used used more than once), how many possible codes (outcomes) can be made?

8^5= 32768 ? Am I wrong?

Repeat #3 above, but this time; how many five letter codes can be made if each chosen letter (from the the original 8 letters) can only be used only once (no repeats).

Repeat #3 above for a five letter code choosing from  the original 8 letters, but this time the letter "b" must be the first letter of the code,  and "f" must be the last letter of the code.  Assume each chosen letter from the original 8 letters given can be used only once (no repeats)

Explanation / Answer

1st) You are right it should be 85 =32768

2nd) for a letter can be used only once : total number of codes =8*7*6*5*4=6720

3rd) as first and last letters are fixed we need to select remainng 3 middle letter out of remaining 6 aplphabets

hence number of codes =6*5*4=120

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