SOLUTION: A number lock has 9 different digits. A combination of three digits can be set to open the lock. How many combinations are possible? Can you explain how I would get the answer 84?
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Question 705160: A number lock has 9 different digits. A combination of three digits can be set to open the lock. How many combinations are possible? Can you explain how I would get the answer 84? Answer by vheroli(126) (Show Source):
You can put this solution on YOUR website! It is a combination therefore you will use nCr.
9C3 = 84
For complete solution:
9! / (6! x 3!) = 84
