I am trying to figure out the maximum possible combinations of a (HEX) string, with the following rules:
- All characters in uppercase hex (ABCDEF0123456789)
- The output string must be exactly 10 characters long
- The string must contain at least 1 letter
- The string must contain at least 1 number
- A number or letter can not be represented more than 2 times
I am thinking the easy way to go here (I am most likely wrong, so feel free to correct me):
- Total possible combinations: $16^{10} = 1,099,511,627,776$
- Minus all combinations with just numbers: $10^{10} = 10,000,000,000$
- Minus all combinations with just letters: $6^{10} = 60,466,176$
- etc...
Can someone could tell me if this is the right way to go and if so, how to get the total amount of possible combinations where a letter or a number occur more than twice.
Any input or help would be highly appreciated!
Muchos thanks!
PS.
I don't know if I tagged this question right, sorry :(
DS.