How many 5 character passwords can be made using the letters A through Z?

Question 473728: how many different five character passwords can be formed from the lowercase letters of the alphabet if repetition in not allowed? If repetition is not allowed, then the amount of combinations is: 23×22=7,893,600 different combinations..

How many different 3 letter passwords are possible if no letter may be repeated?

So, there are total possible values of (xyz).

How many three letter words can be formed allowing repetition?

You can use three distinct letters in P(4,3)=4⋅3⋅2=24 ways. ways to form a word with a repeated letter. Consequently, there are distinguishable three letter words that can be formed with the letters of the word SERIES.

How many 3 letter words can be formed using the 26 letters of the alphabet if repetition of letters is allowed or is not allowed?

If repetition is allowed then each of the 3 letters in the string will all have 4 permutations. Thus the answer is 4 x 4 x 4 = 64.