Question 766583
Suppose a “combination” lock has the numbers 0 to 39 on it. In order to open the lock, a person must dial the correct three number sequence like 12 left, 24 right, 6 left. 

1. How many different three-number sequences are possible assuming that numbers can be repeated?
40*40*40 = 64000
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2. How many different three-number sequences are possible if numbers may not be repeated?
40*39*38