Probability?

#1
Find the total number of outcomes when choosing the last
three digits in a five-digit zip code if the first digit is 6 and the
second digit is 1, and no digit is used more than once.
 
#2
There are 10 digits in total (0, 1, 2,...,9).
Two digits are in use already.
Since no digit is used more than once, we have the following:
For the 3rd digit, there are 10-2=8 choices.
For the 4th digit, there are 10-3=7 choices.
For the 5th digit, there are 10-4=6 choices.

Thus the total number of outcomes is 8*7*6=336

:)