Question 562216: How many five-letter strings can be made from the 1st 10 letters of the alphabet, without replacement?
Answer by issacodegard(60)   (Show Source):
You can put this solution on YOUR website! Hi, the problem is identical to finding the number of 5-lists taken from a 10 set with regard to order (since we are dealing with strings i.e. abcde is not the same as bacde) and without regard to repetition (aabcd is not possible since we are handed the first 10 letters and can't replace one before choosing the next letter).
There are 10 possibilities for the first element in the 5-list, 9 for the next (since we already used the first letter, whatever it was), 8 for the next, 7 for the next, and 6 for the last. So there are 10*9*8*7*6=30240 such strings.
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