There are 24 different arrangements of 4 numbers (4 factorial or 4!). If you allow numbers to be repeated then the figure becomes 256 (44)
24 of them.
INFINITE
I assume you mean how many 4-digit numbers can be made from a set such as {A,A, B, C} where A, B and C are single digits. There are 12 such numbers.
45
None. You do not have enough numbers to make even one combination.
24 of them.
INFINITE
There are 16 4-digit numbers that can be made up from 9 and 6.
I assume you mean how many 4-digit numbers can be made from a set such as {A,A, B, C} where A, B and C are single digits. There are 12 such numbers.
10,000
45
6! = 720
None. You do not have enough numbers to make even one combination.
ten
6*5*4*3=360
The answer is 10C4 = 10!/[4!*6!] = 210
64