There are 15 combinations.
9999
There are 7 combinations. Each combination excludes a different one of the seven numbers.
98,706,816
There is only one combination. The order does not matter in a combination.
120 WRONG! That is the number of PERMUTATIONS. In the case of combinations, the order of the numbers does not matter, so there is only 1 5-number combination from 5 numbers.
Only one, since the order of the numbers does not matter in a combination.
-- 4 numbers can be lined up in 24 different ways-- If the order doesn't matter, then there's only one4-number combination of 4 numbers.
10C6 = 210
There are 360 of them.
If you can repeat the numbers within the combination there are 10,000 different combinations. If you cannot repeat the numbers within the combination, there are 5040 different combinations.
There are 15 combinations.
9999
Since there are infinitely many prime numbers, there can be no such number.
4 of them. In a combination the order of the numbers does not matter.
That depends on the manufacturer. Different brands can have different lengths of serial numbers.
It depends on how many numbers are in each combination. If there are 5 numbers in each combination, then you have 575,757 possibilities. If there are 2 in each combination, there you have 741 possibilities. If there's only 1 number in each combination, then there are only 39 possibilities.