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# Combinations on a combination lock Watch

1. If I took a 10 digit, 3 letter combination lock where the combination could include 1 to 13 digits, would the number of possible combinations be
13C1 + 13C2 ..... + 13C13
2. (Original post by jsmith6131)
If I took a 10 digit, 3 letter combination lock where the combination could include 1 to 13 digits, would the number of possible combinations be
13C1 + 13C2 ..... + 13C13
I don't think so.
Order's important in a combination lock - it's actually a permutation lock but hey ho:
I'm not 100% but the numbers and letters are independent of each other,
So there are ways of making a unique code, assuming you use all the units. Which is considerably larger than what you proposed at around
If you use fewer units as the code, it becomes more and more complicated
3. (Original post by joostan)
I don't think so.
Order's important in a combination lock - it's actually a permutation lock but hey ho:
I'm not 100% but the numbers and letters are independent of each other,
So there are ways of making a unique code, assuming you use all the units. Which is considerably larger than what you proposed at around
If you use fewer units as the code, it becomes more and more complicated
On the lock I am referring to once the order in which the keys are pressed is NOT relevant!!
4. (Original post by jsmith6131)
On the lock I am referring to once the order in which the keys are pressed is NOT relevant!!
There's still the possibility of choosing from 26 possible letters and the 10 digits etc.
5. (Original post by joostan)
There's still the possibility of choosing from 26 possible letters and the 10 digits etc.
no its a 0-9 and X,Y,Z combination lock

6. (Original post by jsmith6131)
no its a 0-9 and X,Y,Z combination lock

Oh. Ok, if the order doesn't matter, are you allowed to hit the same button twice?
7. (Original post by joostan)
Oh. Ok, if the order doesn't matter, are you allowed to hit the same button twice?
no....i.e: if you do it makes absolutely no difference AND the code X739 = 973X.... it makes NO difference which ORDER you push the buttons
8. (Original post by jsmith6131)
no....i.e: if you do it makes absolutely no difference AND the code X739 = 973X.... it makes NO difference which ORDER you push the buttons
In which case, I believe that you were right in your initial post and I've been wasting your time

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