How many combinations are there with 26 alphanumeric number?

Answer 1

It depends on how long would be the resulting string of character and if a character can be repeated or not

1) suppose a string of n characters and characters can be repeated

then for the first character one can choose 1 out of 26, the same for the second and so on then there are 26n solutions

2) suppose a string of n characters and none is repeated

This string would be less than 27 character long then n<27

for the first character one can choose 1 out of 26

for the second character one can choose 1 out of 25 (25 possible characters are left once the first is chosen)

for the third character one can choose 1 out of 24 (24 possible characters are left once the first and the second are chosen)

and so on

so there are 26x25x24x....x(26-n+1) solutions