There are 10 to the 10th power possibilities of ISBN numbers if d represents a digit from 0 to 9 and repetition of digits are allowed. That means there are 10,000,000,000 ISBN numbers possible.
290
If repetition is allowed . . . . . 343 If repetition is not allowed . . . . . 210
if the repetition is allowed the there is 6*6*6 possible ways = 216
Assuming 9 numbers chosen from 56, with no repetition allowed, there are 7575968400 possible combinations.
64 if repetition is allowed.24 if repetition is not allowed.
If repetition of digits isn't allowed, then no13-digit sequencescan be formed from only 5 digits.
When the repetition is allowed: 4*4*4 = 64 numbers. Without repetition: 4*3*2 = 24 numbers.
There are 504 of them.
If repetition of digits is allowed, then 56 can.If repetition of digits is not allowed, then only 18 can.
Possible solutions - using your rules are:- 11,13,17,31,33,37,71,73 &77
There are 5*5*5 = 125 such numbers.