There are 60480 numbers.
There are 900 of them.
27 if the digits can be repeated. 6 if not.
48 of them if digits may not be repeated. 100 if they can.
24 different numbers.
Using the digits of 1345678, there are 210 three digit numbers in which no digit is repeated.
If repetition of digits isn't allowed, then no13-digit sequencescan be formed from only 5 digits.
Possible solutions - using your rules are:- 11,13,17,31,33,37,71,73 &77
the largest five digit number that can be formed using the digits 7 and 9 is 97,000
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