A whole number consists of the digits 2, 4, 6, 8, and 0. If each digit is used only once, how many whole numbers are possible?
120 numbers are possible. You have five spots for numbers.
_ _ _ _ _
Since each digit is used only once, there are 5 possibilities for the first digit, 4 for the next, 3 for the next, and so on.
5 4 3 2 1
5 x 4 x 3 x 2 x 1 = 120
using the digits of 2, 4, 6, 8, and 0 as a number and only using them once, you could possibly have 120 different numbers. You can get this by having a choice of 5 numbers for the first digit, 4 numbers for the second digit and so on...leaving the problem of 5! (five factorial....5x4x3x2x1 = 120)