45
If the 6 digits can be repeated, there are 1296 different combinations. If you cannot repeat digits in the combination there are 360 different combinations. * * * * * No. That is the number of PERMUTATIONS, not COMBINATIONS. If you have 6 different digits, you can make only 15 4-digit combinations from them.
Assuming the digits cannot be repeated, there are 7 combinations with 1 digit, 21 combinations with 2 digits, 35 combinations with 3 digits, 35 combinations with 4 digits, 21 combinations with 5 digits, 7 combinations with 6 digits and 1 combinations with 7 digits. That makes a total of 2^7 - 1 = 127: too many for me to list. If digits can be repeated, there are infinitely many combinations.
Just one.
There are infinite combinations that can make 3879
45
If the 6 digits can be repeated, there are 1296 different combinations. If you cannot repeat digits in the combination there are 360 different combinations. * * * * * No. That is the number of PERMUTATIONS, not COMBINATIONS. If you have 6 different digits, you can make only 15 4-digit combinations from them.
9,000 - all the numbers between 1,000 and 9,999 inclusive. * * * * * NO. Those are PERMUTATIONS, not COMBINATIONS. Also, the question specified 4 digit combinations using 4 digits. The above answer uses 10 digits. If you start with 4 digits, you can make only 1 combination.
Assuming the digits cannot be repeated, there are 7 combinations with 1 digit, 21 combinations with 2 digits, 35 combinations with 3 digits, 35 combinations with 4 digits, 21 combinations with 5 digits, 7 combinations with 6 digits and 1 combinations with 7 digits. That makes a total of 2^7 - 1 = 127: too many for me to list. If digits can be repeated, there are infinitely many combinations.
With 4 digits you can have 24 = 16 combinations. 1 combination with 0 digits; 4 combinations with 1 digit: 1, 2, 4 and 8 6 combinations with 2 digits: 12, 14, 18, 24, 28 and 48 4 combinations with 3 digits: 124, 128, 148 and 248 1 combination with all 4 digits. In a combination the order of digits is not relevant so that 124 is the same as 142.
120 combinations using each digit once per combination. There are 625 combinations if you can repeat the digits.
Just one.
There are infinite combinations that can make 3879
10C6 = 10*9*8*7/(4*3*2*1) = 210 combinations.
6 for 3-digits, 6 for 2-digits, 3 for 1-digits, and 15 for all of the combinations
Only one: 2468. The order of the digits in a combination does not make a difference.
If you have 4 positions, each of which can hold any of the ten digits, you have 10 to the power 4 combinations. If you can have only 4 different digits, you have 4 to the power 4 different combinations.