Question 888585
if repetitions are allowed, then 27^5 = 14348907
if repetitions are not allowed, then 27P5 = 27! / 22! = 9687600


how's this work?


in order to see, try 2 letter code words from 3 letter alphabet of abc.


with repetition = 3^2 = 9
without repetition = 3P2 = 3! / 1! = 6


with repetition, the codes would be:


aa
ab
ac
ba
bb
ac
ca
cb
cc


total of 9.


without repetition, the codes would be:


ab
ac
ba
bc
ca
cb


the same formulas apply to the bigger problem.


the formula for permutation is nPx = n! / (n-x)!