5 ^12
If repetition of digits isn't allowed, then no13-digit sequencescan be formed from only 5 digits.
5040
1000
290
There are 2000 such numbers.
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.
-4
If repetition of digits is allowed, then 56 can.If repetition of digits is not allowed, then only 18 can.
64 if repetition is allowed.24 if repetition is not allowed.
There are 2000 such numbers.
Possible solutions - using your rules are:- 11,13,17,31,33,37,71,73 &77
125 different 4 digits numbers. To be divisible by 4, the last two digits must be divisible by 4, which means they must be: 12, 24, 32, 44 or 52 - 5 possible choices. For each of these there are 5 choices for the first digit and 5 for the second, meaning: total = 5 x 5 x 5 = 125