SOLUTION: to open a combination lock, you must dial a 3-digit combination using the digits 0-39. How many combinations are possible ... a) if repeating a digit is allowed b) if repeating

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Question 305601: to open a combination lock, you must dial a 3-digit combination using the digits 0-39. How many combinations are possible ...
a) if repeating a digit is allowed
b) if repeating a digit is not allowed
Found 2 solutions by stanbon, Alan3354:
Answer by stanbon(75887) (Show Source):
You can put this solution on YOUR website!
to open a combination lock, you must dial a 3-digit combination using the digits 0-39. How many combinations are possible ...
a) if repeating a digit is allowed::::39^3
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b) if repeating a digit is not allowed::: 39*38*37
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Cheers,
Stan H.
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Answer by Alan3354(69443) (Show Source):
You can put this solution on YOUR website!
0-39 is 40 numbers
If repeats are allowed, it's 40^3 = 64000
If not, it's 40*39*38 = 59280
If repeats are allowed, but not consecutive repeats, it's 40*39*39 = 60840