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.
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
6! = 720
6*5*4*3=360
There are 5*4*3 = 60 such numbers.
20 of them, if repetition is not allowed.
64
2
Egyptians made the numbers 4 back in B.C.
With repeats: 4×4 = 16; Without repeats: 4×3 = 12.
15