Byron bought a keyless entry door lock that has the digits 0 through 9 on the keypad. He wants to choose a three-digit entry code. How many different combinations are possible, if the digits can be repeated?
27
30
729
1,000
There are, 3 x 2 x 1 = 6 possible ways of arranging the three digits. Therefore in that set of 720 possibilities, each unique combination of three digits is represented 6 times. So 720 different combinations are possible.
