There is only one possible combination of a 13 digit number created from 13 digits.
In a combination, the order of the digits does not matter so that 123 is the same as 132 or 312 etc.
If there are 13 different digits (characters) there is
1 combination of 13 digits
13 combinations of 1 or of 12 digits
78 combinations of 2 or of 11 digits and so on
There are 213 - 1 = 8191 in all.
If the characters are not all different it is necessary to have more information.
If the same 7 digits are used for all the combinations then n! = 7! = 7*6*5*4*3*2*1 = 5040 combinations There are 9,999,999-1,000,000+1=9,000,000 7-digit numbers.
Too many to list here-see below.
if its not alphanumeric, 999999 variations
How many four digit combinations can be made from the number nine? Example, 1+1+2+5=9.
Just 4: 123, 124, 134 and 234. The order of the numbers does not matter with combinations. If it does, then they are permutations, not combinations.
There are twelve possible solutions using the rule you stated.
There are 210 4 digit combinations and 5040 different 4 digit codes.
105 = 100000
There are 5,040 combinations.
There are 5,461,512 such combinations.
64
There are 27 possible combinations.
56 combinations. :)
Number of 7 digit combinations out of the 10 one-digit numbers = 120.
There are 4,500 combinations.
Allowing leading zeros, 109 or 1 billion.
If the same 7 digits are used for all the combinations then n! = 7! = 7*6*5*4*3*2*1 = 5040 combinations There are 9,999,999-1,000,000+1=9,000,000 7-digit numbers.