If every number can be used as many times as you like, there are 104 = 10000 different combinations. If each number can only be used once, there are 9!/(9 - 4)! = 5040 combinations.
9!/5! or 3024
There are 9C2 = 9*8/(2*1) = 36 2-digit combinations.
There are 10 choices for the first number, 9 for the second and 8 for the third. 10*9*8=720 possible combinations.
44
There are 45 combinations.
9!/5! or 3024
There are only 10 combinations. In each combination one of the 10 digits is left out.
The number of combinations is 10C4 = 10*9*8*7/(4*3*2*1) = 210
10,000 http://wiki.answers.com/
900000
9
10P4 = 5040
In most 3-number locks, each number ring offers a choice of 10 digits, from 0 to 9. I that case, there are 103 = 1000 combinations.
The number of combinations of 7 numbers from 10 is 10C7 = 10*9*8/(3*2*1) = 120
I need to have listed all the 4 number combinations between 1 and 9
How many four digit combinations can be made from the number nine? Example, 1+1+2+5=9.