Question 1057352
a. Repetition is not allowed:


Assuming that the three digit number cannot begin with 0, there are four choices for the 
first digit (1, 3, 5, 6), and then four choices for the second digit (because the first choice is 
eliminated, but 0 is possible), and then three choices for the third digit.


The number of possible three-digit numbers is then:


4 * 4 * 3 = 48


b. Repetition is allowed:


Again assuming that the three digit number cannot begin with a 0, there are four choices for
the first digit, and then all five choices for the second digit, and five choices for the third digit.


The number of possible three-digit numbers is:


4 * 5 * 5 = 100