Possible solutions - using your rules are:- 11,13,17,31,33,37,71,73 &77
900 ,999 ,909
If repetition of digits isn't allowed, then no13-digit sequencescan be formed from only 5 digits.
There are 2 possible digits for the first digit (3 or 4), leaving 3 possible digits for the second digit (5 and 6 and whichever was not chosen for the first), leaving 2 possible digits for the third. Thus there are 2 × 3 × 2 = 12 possible 3 digit numbers.
2 * 2 * 2 * 2 It's not possible to make 16 without using the same numbers twice or without using whole numbers.
The possible 4 digit codes using the numbers 0-9 are every number between 0 and 9999. For numbers that have less than 4 digits, just precede the number with 0's. 10,000 possibilities
1000
10,000
There are 10000 such codes. Each of the numbers 0-9 can be in the first position. With each such first digit, each of the numbers 0-9 can be in the second position. With each such pair of the first two digits, each of the numbers 0-9 can be in the third position. etc.
Possible solutions - using your rules are:- 11,13,17,31,33,37,71,73 &77
900 ,999 ,909
290
Possible 5 digit combinations using 5 digits only 1 time is 5! or 5*4*3*2*1 or 120. Using 5 digits where numbers can be used 5 times is 55 or 3125.
If repetition of digits isn't allowed, then no13-digit sequencescan be formed from only 5 digits.
There are 2 possible digits for the first digit (3 or 4), leaving 3 possible digits for the second digit (5 and 6 and whichever was not chosen for the first), leaving 2 possible digits for the third. Thus there are 2 × 3 × 2 = 12 possible 3 digit numbers.
2 * 2 * 2 * 2 It's not possible to make 16 without using the same numbers twice or without using whole numbers.
There are 4 possible numbers if the digits are not repeated; 18 if they are. Those are 3-digit numbers, assuming that zero would not be a leading digit. If zero is allowed for a leading digit, then you can have 6 for the non repeated, and 27 if repetition.