How many 4 number combinations are there in the numbers 0 to 9?

Answer 1

The easy answer is 0000 thru 9999, which is 10,000 combinations. A way to calculate this is by Nx

where N is the number of digits possible (here, 10 different digits are

possible) 0 through 9, and x is the number of places available (here we have 4 places available for a 4 digit number)

note the formula is N raised to the x power

meaning, 104

or 10 X 10 X 10 X 10 = 10,000 combinations

Another exampleHow many combinations are available using digits 0-3 for a 2 digit number?

The possibilities are: 00 01 02 03 10 11 12 13 20 21 22 23 30

31 32 33

or 16 possibilities

the formula would tells us:

Nx is 42 or 4 x 4 = 16

* * * * *

THE ABOVE ANSWER IS WRONG!

Interesting but completely wrong since the answer confuses permutations and combinations. The combination 12 is the same as the combination 21.

The number of 4 digit combinations from the numbers 0 to 9 is 10C4 = 10!/[4!*6!]

=10*9*8*7/(4*3*2*1) = 210.