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.
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
6! = 720
6*5*4*3=360
how many combinations of 4 numbers are there in 7 numbers
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.