Let's consider the following distribution:
__ __ __
Each space represents one number.
The first number can be anything from 0-9 (10 possibilities).
The second number, after choosing the first number, can only have 9 possibilities. The reasoning behind this is if we choose the same number as the first, then there is a repetition. So we can't use that same number again.
The third number can only have 8 possibilities by the same logic as for the second digit.
Therefore there can be 10*9*8 = 720 3-digit numbers with no repetitions of digits.
If repetition of digits isn't allowed, then no13-digit sequencescan be formed from only 5 digits.
I take it that you want to make three digits numbers with 8,7,3, and 6 without repetition. The first digit cane be selected from among 4 digits, the second from 3 digits, the third digit from 2, hence the number of three digit numbers that can be formed without repetition is 4 x 3 x 2 = 24
64 if repetition is allowed.24 if repetition is not allowed.
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.
Six (6)
If repetition of digits isn't allowed, then no13-digit sequencescan be formed from only 5 digits.
24 three digit numbers if repetition of digits is not allowed. 4P3 = 24.If repetition of digits is allowed then we have:For 3 repetitions, 4 three digit numbers.For 2 repetitions, 36 three digit numbers.So we have a total of 64 three digit numbers if repetition of digits is allowed.
I take it that you want to make three digits numbers with 8,7,3, and 6 without repetition. The first digit cane be selected from among 4 digits, the second from 3 digits, the third digit from 2, hence the number of three digit numbers that can be formed without repetition is 4 x 3 x 2 = 24
If the number can contain repeated digits, the answer is 800000. Without repetition, there are 483840.
64 if repetition is allowed.24 if repetition is not allowed.
There are 7,290 different 4-digit numbers that can be formed from the digits 1-9 without repetition.
-4
If repetition of digits is allowed, then 56 can.If repetition of digits is not allowed, then only 18 can.
-123456787
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
You have seven different digits (symbols) to choose from, so you can form seven different one digit numbers and 7×7=72=49 different two digit numbers.