Using only the numbers 1,3,5,7,9, and using each number only once, we have 5 options for the first digit, then 4 remaining options for the second, 3 remaining options for the third and 2 remaining options for the fourth. This means there are 5x4x3x2 ways to combine the digits 1,3,5,7,9 into a 4 digit number. 5x4x3x2=120, so there are 120 four digit numbers that can be made.
There are 60480 numbers.
There are 900 of them.
48 of them if digits may not be repeated. 100 if they can.
There are 25 such numbers.
There are 2000 such numbers.
There are 60480 numbers.
There are 900 of them.
27 if the digits can be repeated. 6 if not.
27
24 different numbers.
48 of them if digits may not be repeated. 100 if they can.
More than one
If repetition of digits isn't allowed, then no13-digit sequencescan be formed from only 5 digits.
6
Possible solutions - using your rules are:- 11,13,17,31,33,37,71,73 &77
Using the digits of 1345678, there are 210 three digit numbers in which no digit is repeated.
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