None. You do not have enough numbers to make even one combination.
9
8C3 = 56 of them
137, 173, 317, 371, 713, 731 Six combinations can be made.
There are 23C3 = 23!/(20!*3!) = 23*22*21/(3*2*1) = 1,771 combinations.
3! or 6 combinations can be made from three distinct numbers. For this example they are: 345, 354, 534, 543, 435, 453.
None. You do not have enough numbers to make even one combination.
Six combinations: 123, 132, 213, 231, 312, 321
9
You can make 5 combinations of 1 number, 10 combinations of 2 numbers, 10 combinations of 3 numbers, 5 combinations of 4 numbers, and 1 combinations of 5 number. 31 in all.
6 ways: 931,913,139,193,391,319
There are 32C3 = 32*31*30/(3*2*1) = 4960 combinations. I do not have the inclination to list them all.
8C3 = 56 of them
Only three: 12, 13 and 23. Remember that the combinations 12 and 21 are the same.
137, 173, 317, 371, 713, 731 Six combinations can be made.
There are 23C3 = 23!/(20!*3!) = 23*22*21/(3*2*1) = 1,771 combinations.
If the numbers can be repeated and the numbers are 0-9 then there are 1000 different combinations.