Use the counting principle to determine the number of elements in the sample space. Two digits are selected without replacement from the digits 1, 2, 3, and 4.

if the order of the digit matters, we have:

options: 1, 2, 3, 4.

We want to select two digits.

First selection: we have 4 options

Second selection: we have 3 options (because we already selected one in the first selection)

The total number of elements in the sample space, or the total number of combinations, is equal to the product of the number of options in each selection, this is:

P = 4*3 = 12

a negative exponent is translated as follows:

so, we have