14 combinations.
Two make combinations you would take 2x1=2 combinations only
You could make 10*10*10*26*26*26 combinations, or 17576000 combinations.
Assuming you are using the standard English alphabet, the number of combinations you can make are: 26 x 26 = 676 combinations.
9
Assuming the digits cannot be repeated, there are 7 combinations with 1 digit, 21 combinations with 2 digits, 35 combinations with 3 digits, 35 combinations with 4 digits, 21 combinations with 5 digits, 7 combinations with 6 digits and 1 combinations with 7 digits. That makes a total of 2^7 - 1 = 127: too many for me to list. If digits can be repeated, there are infinitely many combinations.
8x7x6x5x4x3x2x1
23
Unlimited.
20
720
You can make 5 combinations of 1 number, 10 combinations of 2 numbers, 10 combinations of 3 numbers, 5 combinations of 4 numbers, and 1 combinations of 5 number. 31 in all.
25 different combinations.