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PAHH
Oct19-10, 05:14 PM
Hello all:
This may be the only question I ever ask here, so pardon if I posted in wrong forum.

I work for Habitat for Humanity, a non-profit 501(c) (3) org. A local business donated an open floor safe without a combination. We could really use this safe in our office. The manufacturer no longer has the master combination and want over $500 to come out to fix. We can't afford that, but from looking at the keypad, there are 4 numbers that look dirty and well used. Those numbers are: 2587

Can anyone provide me a list of all the number combinations possible for those four numbers?
turbo
Oct19-10, 05:30 PM
Does one of the keys look much more worn/dirty than the other three? If they are all equally worn, maybe you are lucky, and there are only 10,000 combinations to try.
Borek
Oct19-10, 05:34 PM
If you start with 2, next digit can be 5, 7 or 8:

25
27
28

In each case there are only two digits left and they can be in two different orders. Repeat for 5 (followed by 2, 7, 8), 7 (followed by 2, 5 8) and 8 (you should see the pattern now).

That is, assuming combination is four digits. If it is longer it will be more complicated.
PAHH
Oct19-10, 05:35 PM
Does one of the keys look much more worn/dirty than the other three? If they are all equally worn, maybe you are lucky, and there are only 10,000 combinations to try.

Thanks for response. As I said: "but from looking at the keypad, there are 4 numbers that look dirty and well used. Those numbers are: 2587."


Much appreciated
Borek
Oct19-10, 05:37 PM
Surprising, how similar to some homeworks this question is...
turbo
Oct19-10, 05:45 PM
Does one of the keys look much more worn/dirty than the other three? If they are all equally worn, maybe you are lucky, and there are only 10,000 combinations to try.Oops! :redface: Silly me.
turbo
Oct19-10, 05:49 PM
Not that many possible combos when there are only 4 keys in a 4-number combo. WAY not.
PAHH
Oct19-10, 05:59 PM
Surprising, how similar to some homeworks this question is...

Thanks Borek, but no one has "carded" me in over a decade. I also have gray hair for all that's worth, but if you are afraid of providing an answer, thats fine. Actually, my concern was not being perceived as a snot nosed child, but as a burgler. I assure you, I am as I stated.
turbo
Oct19-10, 06:04 PM
Let's pretend the worn keys are "1", "2", "3", and "4" and that they are equally worn and dirty. Best-case means that you have a 4-digit combination. If the combo starts with "1", you can have:
1234
1243
1324
1342
1423
1432

That's 6 possible sequences. If you substitute "2", "3" and "4" for the "1" and write down those combinations, it's a pretty short list.